Or can someone point me to the relevant sections of the books that talks about this stuff, please?
Reason I ask is that I'm trying to gauge the cost of living in Faerun and I plan on repricing some items. E.g. Sunrods - 4gp seems cheap to me, but not if a pint of beer costs 3 copper, for instance.
If you want a complete set of D&D style prices then I recommend looking at Expeditious Retreat Press Silk Road. It has a comprehensive compilation of all kinds of goods and attendent price information. You can get the book here and the PDF here.
There is this which is a price list used for Harn. A pretty version is here. 1d = one silver penny = one silver piece. 4 farthings = 1 silver penny = 2.5 copper pieces.
All of this is useful because the Forgotten Realms uses the standard D&D pricing for goods and services. I personally use a Modified Harn system because there is some research behind the prices making more a more consistent system of values. Silk Road is likewise well researched although it been tweaked to be usable with d20 products especially on the more exotic/magical items.
3 D&D cp = one pint of beer = 1 farthing so the D&D price for a beer isn't that far off. Actually a little more expensive. What you really want to look at is how long it takes to make that sunrod. A 4 gp per, the price is comparable to some of the more expensive tools (a plough for example) or animals (4 sheep, or 2 pigs). But it of limited duration so their use would be limited to the more wealthy individuals of society.
One way to figure the true price a magic item is look at how long it takes to make, and how much does it cost to make. For a sunrod it makes a difference whether 20 can be produce a month or only 2. Finally magic items will be like luxury items if they can be made reliably. Think of a Damacus steel sword, silk, or a suit of articulated plate armor. All items that require a considerable amount of time and material to produce. This assume of course that magic items are crafted on a regular basis and not some special one time deal. Referee differ in how they approach. My own Majestic Wilderlands treats Magic Items as a high value luxury item.
There was a supplemental book entitled "Aurora's Whole Realms Catalog" which was kind of a shopper's guide to the forgotten realms. Wasn't a very thick book but it had common items and prices. You could use that as a base.
According to my (precious) copy of Aurora's Whole Realms Catalog, p. 131, standard table wine can be had in bulk at wholesale prices for 20 gp for a tun, which is about† 256 gallons. There are about† 8 pints in a gallon, giving a wholesale cost of [20gp / (256 gallons x 8 pints/gallon) ≈ 0.0098gp] slightly less than 1cp per pint to the inn or tavern keeper. With a typical markup of 2x or 4x, that makes cheap table wine somewhere between 2–4cp a pint, which is a lot of wine for not much.
Alternatively, look at the cost of hirelings. The price lists for the Forgotten Realms were originally developed in 1st and 2nd edition AD&D, so the original Dungeon Master's Guide is useful for various incomes. There is a list of occupations on p. 28 and their cost to hire for a day or month. The income of a skilled labourer (mason, carpenter, teamster) is from 2gp to 5gp per month, assuming their lodging is provided by their employer. Judging from that, a 4gp Sunrod is akin to buying half of a wedding ring for a middle-class worker.
†I say "about" because it's unclear whether the Realms use Earth Imperial or Earth US Standard measurements, and Earth measurements have had their definitions changed multiple times since our own mediæval age anyway.
This may not be the answer you are looking for.
But I run games with very heavy social interplay; where PC's adventure for reason, and where details matter for immersion.
How does this apply to this question? Details create a more realistic game. Do you go out to a bar and just ask for 'a beer'? Yes, very primitive cultures or small population centers might have limited choices, but cities and such or semi-sophisticated areas should have a large amount of variety.
And it motivates a PC to be able to afford what common folk cannot.
Here is the Booze that can be found in Igbar, capital of Trabler. SO I don't know how much in Faerun, but choice and different quality levels makes for a more fun player experience.
And this affects the price of living heavily. Understanding what lies in the level of the lower class, the middle class and the upper class is needed to understand the economy.
