Determining artifact treasure value

Question

Major and minor artifacts are listed in several D&D books, but how does one determine their worth? Obviously they are worth something to an adventurer much like a magical location; magical locations are assigned a treasure value but from what I can tell many artifacts are not.

For instance the Naja Fountain from Serpent Kingdoms is basically a magical location (though it is described as an artifact)

The effective arcane caster level of anyone who bathes in the Naja Fountain permanently increases by +3. This benefit can be gained only once per creature. Furthermore, immersion in the fountain's waters confers the benefits of a heal spell for every round of immersion. Finally, any living creature in contact with the fountain's water is immortal and does not age, though these benefits are lost if the creature ceases contact with the water. The water loses all magical powers when removed from the fountain.
Overwhelming conjuration; CL 21st; Weight: N/A (immovable).
Source: Serpent Kingdoms

This is obviously worth a great deal to a player but no gold amount is assigned to it. In contrast magical locations are assigned specific treasure value.

Is there s way to determine artifact value or are artifacts not meant to have a gold value?

Answer 1

So something having no explicit value can mean one of two things:

1. it is worthless, or

2. it is priceless

Artifacts are in the latter category.

Artifacts should never be bought or sold; there shouldn’t be any amount of gold that would be acceptable to purchase one. If the players wanted to sell one, they’re looking at arranging an auction for it (and that means providing for security for the artifact as well as the event and its fabulously wealthy patrons). Likewise, the only place player characters are going to see one for sale is at such an auction.

Artifacts are, first and foremost, plot drivers and world builders, not gear (though they may, of course, be incredibly useful as gear). Artifacts break the rules, and that includes the rules of the game’s economy. They are purely within the DM’s purview, and should be handed out solely when he or she wishes to do so for the purposes of the plot. And that plot shouldn’t (usually, going by the wealth-by-level guidelines) cost the players gold. It should be much bigger than that.

Answer 2

From the 3.5 DMG:

Artifacts are extremely powerful. Rather than merely another form of magic equipment, they are the sorts of legendary relics that whole campaigns can be based on. Each could be the center of a whole set of adventures -- a quest to recover it, a fight against an opponent wielding it, a mission to cause its destruction, and so on. No table has been included to randomly generate specific artifacts, since those items should only enter a campaign through deliberate choice on your part.

There are also a couple of notes identifying artifacts as uncraftable by players; since the rules detail how crafting works based primarily on gold cost, not including approximate GP costs may have been a further effort to restrain players' ambitions.

Since in point of fact some artifacts are not that powerful, GP costs can often be approximated by using the rules for crafting magical items (which assign GP cost by spell effects and passive bonuses provided). In the case of the artifact described, the Heal effect alone is worth (spell level x caster level x 2000 x 1.5 for nonstandard slot) = 378000 GP based on the Estimating Magic Item Cost table. Deciphering the value of the other effects would require analyzing other, similar magic items or spell effects to approximate.