What's the maximum possible wealth bonus that a d20modern character can achieve by 10th level, excluding DM intervention? What is the max at 20th level? How rich would such a character be in real world dollars?
The conditions required to get the maximum possible wealth bonus are very artificial, but for the sake of argument let's assume the following:
- Dilettante taken as Profession
- an 8 rolled on 2d4 for starting wealth
- rolling 18 for Wisdom at character creation
- always rolling 20 on wealth checks when leveling up
- every feat spent on Windfall
- always spending the maximum skill points on Profession (max rank = level + 3)
- always increasing Wisdom
- never buying anything that requires a wealth check
- the DM completely ignores wealth, neither granting it nor threatening it
Such a character can start with a wealth bonus of +20 at 1st level (8 from the 2d4 roll, +6 for Dilettante, and +3 x2 from taking Windfall twice).
At level-up, there are three ways the wealth bonus might increase:
- Succeeding on a Profession check, which gives +1, and an additional +1 for each margin of 5 that the roll passes the DC. Note that the DC is the current wealth bonus.
- Buying the Windfall feat again, which gives a flat +3 bonus to wealth each time its bought. (And which also gives +1 to Profession rolls to increase wealth when leveling up.)
- There is a flat increase to wealth when leveling up, depending on how many ranks in Profession the character has. e.g., +1 for Rank 1-5, +2 for Rank 6-10, etc.
So we can figure out what the maximum theoretical wealth increase is for each level by tracking the things that give bonuses to the Profession roll (Wisdom, Windfall feats, and ranks in Profession), and comparing that to the current wealth rating (which is the DC for Profession checks when leveling up). We can then calculate the maximum bonus from the Profession roll, from new Windfall feats, and from the flat bonus from having ranks in Profession. That's summarised in the following table.
S Increases t W ——————————————————————— C a e T M L R F h B r a M | F R o | a B e a e e o t l a R | R e a t I | x o v W n a c n i t x o | o a n a n | n e i k t k u n h l | l f k l c | u l | s | s | s | s | g | l | l | s | s | r.| s ———+————+———+—————+——————+———————+—————+————+————+————+——————+—————— 1: 18 4 x2 | — +20 — | — — — — | +20 2: 18 5 x3 | +12 +20 32 | +3, +3, +1, +7 | +27 3: 18 6 x4 | +14 +27 34 | +2, +3, +2, +7 | +34 4: 19 7 x5 | +16 +34 36 | +1, +3, +2, +6 | +40 5: 19 8 x5 | +17 +40 37 | +0, +0, +2, +2 | +42 6: 19 9 x7 | +20 +42 40 | +0, +6, +2, +8 | +50 7: 19 10 x7 | +21 +50 41 | +0, +0, +2, +2 | +52 8: 20 11 x8 | +24 +52 44 | +0, +3, +3, +6 | +58 9: 20 12 x9 | +26 +58 46 | +0, +3, +3, +6 | +64 10: 20 13 x10 | +28 +64 48 | +0, +3, +3, +6 | +70 11: 20 14 x10 | +29 +70 49 | +0, +0, +3, +3 | +73 12: 21 15 x12 | +32 +73 52 | +0, +6, +3, +9 | +82 13: 21 16 x12 | +33 +82 53 | +0, +0, +4, +4 | +86 14: 21 17 x13 | +35 +86 55 | +0, +3, +4, +7 | +93 15: 21 18 x14 | +37 +93 57 | +0, +3, +4, +7 | +100 16: 22 19 x15 | +40 +100 60 | +0, +3, +4, +7 | +107 17: 22 20 x15 | +41 +107 61 | +0, +0, +4, +4 | +111 18: 22 21 x17 | +44 +111 64 | +0, +6, +5, +11 | +122 19: 22 22 x17 | +45 +122 65 | +0, +0, +5, +5 | +127 20: 23 23 x18 | +47 +127 67 | +0, +3, +5, +8 | +135
- Level is the level just gained.
- Wis is the character's Wisdom.
- Ranks is ranks in Profession.
- Feats is how many times the Windfall feat has been taken.
- Check Bonus is the bonus to Profession checks for determining wealth bonus increases when leveling up. (Wis bonus + Profession ranks + 1 per Windfall feat.)
- Starting Wealth is the wealth bonus before calculating the increase for this level. It's used as the DC of the Profession check.
- Max Roll is the maximum possible Profession check: rolling 20 + check bonus from the earlier column.
- Increases are the three ways the wealth bonus could increase that level, and their total:
- Roll is the increase from a perfect 20 roll on the Profession check.
- Feats is the increase from Windfall feats taken at that level (+3 per feat)
- Ranks is the flat increase according to p. 70 due to the number of ranks in Profession.
- Total is the total increase in wealth bonus for that level, and will be applied to the next level in the table.
- Max Bonus is the final, maximum wealth bonus possible at that level, as a sum of the Starting Wealth column and the Increases: Total column.
As you can see, the wealth bonus quickly becomes so large that it becomes impossible to beat the DC on the Profession check even when rolling perfect 20s. (And note that 20 is not an automatic success, see p. 44 Skill Checks.) After 4th level, only the Windfall feats and the flat bonus matter.
So, the maximum wealth bonus at 10th level is +70 (wealth bonus starts at +64, plus the total increase of 6), and the maximum wealth bonus at 20th level is +135 (wealth bonus starts at +127, plus the total increase of +8).
As for how much that is in real-world dollars, according to the system there is no way to translate it into dollars:
[The] Wealth bonus [is] a sort of composite of her income, credit rating, and savings. […] Wealth is not a direct representation of a character's salary or how much money the character has socked away in the bank. […] The Wealth bonus simply represents your character's buying power at any given time.
So a character with +70 Wealth is rich enough that credit is easy enough to come by that they almost never need to worry about money. For comparison, the table on p. 38 calls +31 and higher "Very rich". The only purchase that could even be noticed by such a character (i.e., which would drop their wealth by any amount) would have to have a Purchase DC of 85, which means they could have as many mansions (Purchase DC 36), Learjets (Purchase DC 40), or M1A1 Abrams tanks (Purchase DC 47) as they wanted to own. The only way money would ever be an object would be if the GM set an exorbitant custom DC for, say, buying a very large rival company.
A character with +135 Wealth is so exceedingly rich that they don't ever have to even think about money—their wealth is so great that everyone knows they're good for it, and their vast network of accountants pays for everything out of the complex financial empire they own. They probably don't even know exactly how much they're worth, and considering how the stock markets work, their exact wealth is probably impossible to know until they tried to use every last penny of it, at which point there would probably be world-wide financial panic. They can probably buy entire countries, unofficially.
@SevenSidedDie has covered the first part of the question thoroughly. As for conversion to real world dollars, there is a table on page 145 of d20 Future (ISBN:0786934239):
Purchase DC Item Cost 2 $5 15 $500 20 $2,000 30 $35,000 40 $650,000 50 $12,000,000 60 $200,000,000 70 $3,500,000,000 80 $65,000,000,000
The relationship between purchase DC and item cost is roughly exponential:
Note that this is the price of an individual item that a character might purchase - not his or her total net worth.
Any time a character buys an object or service with a purchase DC of 15 or higher, the character reduces his or her current Wealth bonus by an additional 1 point.
For example, a character with +64 wealth bonus would lose 1 point when purchasing an item valued between $500 and $650,000,000; 2 points for items between $900 million and $12 billion; 1d6+1 points for items between $15 billion and $50 billion; and 2d6+1 points for items costing more than $50 billion (provided that they succeed on their wealth check).
Regarding large starships:
Most d20 Modern campaigns are set at Progress Level 5.
GMs who want to make lower-PL and higher-PL items available to characters should adjust the purchase DCs of items as follows:
- -2 to Purchase DC for each Progress Level lower than the current Progress Level, except in the case of valuable antiques.
- +5 to Purchase DC for equipment from the next highest Progress Level (the limit for purchasing cutting-edge technology).
d20 Future Tech (ISBN:0786939494) has some example starships and mecha, including a PL6 light freighter with Purchase DC 56 (+5 if purchased in PL5) and an orbital colony with Purchase DC 72.
Given that the Space Shuttle Endeavour cost approximately $1.7 billion (Purchase DC 67), that seems a little low. The International Space Station, believed to be the most expensive object ever constructed, cost between 35 and 150 billion dollars (Purchase DC 78 to 83).
If you manage to roll an 8, add 6 for the Dilettante Profession, and 6 more for Windfall x2, you'll start with 20.
If you're allowing cybernetics and have PL9, you can buy windfall as a cybernetic feat implant at DC 26. If you succeed 4 times, your wealth would be 22, 24, 26, 29. Once you are above 28, you can buy a Feat Plex (PL8) at dc 28, and fill it with 3 windfalls and a cybertaker feat.
You can repeat this as many times as you would like and have infinite wealth and every feat in the game at first level.