GURPS Basic Set assumes that characters can go to shops, stores, or whatever and exchange currency for whatever item they are seeking. This is built in deep to the system and several advantages (Wealth, Status, Independent Income, etc.) rely on it. Now, this does work for most campaigns, but what about post-apocalyptic campaigns where the coin of the realm is bottlecaps or bullets or similar items? What about TL0 societies that haven’t invented coinage yet? In such games Wealth as written probably doesn’t exist. In fact, for such games you really ought to just ignore the Wealth rules entirely and give everyone a flat amount to buy their starting gear. This tends to ask more questions than it answers. What about settled NPCs or PCs who can amass wealth by staying in a single location? What about wandering PCs who bring their spoils back to a specific place? Granted, a good chunk of that can just be written off as “stuff I got in play.” What about creating a new statistic to help simulate the sort of give and take you see in movies, fiction, TV shows, and the like?
Each level of Bartering Capacity represents 5% of the campaigns Starting Wealth (p. B00) that you have in goods, services, or a “line” on where you can get such things. This is intentionally abstract and might include any item or a LC less than the CR of the setting that are common. You may specify what you have if the GM allows as long as you don’t try to “sell back” to yourself by keeping items. In most cases the GM will need to be very strict on what a character could have found or come across during his time. Use the Commercial Transactions rules (p. B561) for the actual bartering process. After a deal is struck your Bartering Capacity goes down and you get the goods or services you’ve bargained for.
Services bartered away require a bit more detail. The player should first tell the GM what services he’s bartering away. The GM should then use either an existing job entry (e.g., GURPS Bio-Tech, p. 208-209 has a entry for a general practitioner which is considered a Wealthy job) or make up a appropriate number. Then divide monthly rates by 25 (for a day of provided services) or by 200 (for one hours worth). Then take the resulting number and compare it to the Starting Wealth of the campaign and convert it that to a Bartering Capacity level. For example, if a character who is a medically trained doctor (Diagnosis and Physician at skill 12 or better) in a TL6 post apocalyptic game could barter away his services at around $320 per day or $40 a hour. This translates to about 4 levels of Bartering Capacity for a day or 1 level of Bartering Capacity for 2 hours of work.
While it may seem the best way to get things is to barter services vs. goods, this requires that you stay in one place for a while and have the skills to begin with. Less than satisfactory services due to failures (especially critical failures) could land the PC in hot water with the locals resulting in reaction penalties, hostile interaction, or even combat should they fail to live up to their end of the bargain!
Bartering Capacity can go up or down during gameplay like any other trait and may be bought up using unspent character points like any other trait.
Picking Over the Bones
I’m sure there are some incongruities in the system I’ve presented – edge cases I haven’t thought of or rules that could use some tightening, but overall this seems like a workable idea – especially for one that came to me in a dream. Of course, I rarely use the RAW Wealth rules (I like PK’s rules and use them for all my campaigns), not because I find them distasteful, but because PK’s alternate ones work better in my experience. Now I wonder should I expand on this and submit it to Pyramid? It’s not a bad little rule and we don’t really have anything for barter and trade in GURPS.