GURPS does have some native bartering rules (they're in Social Engineering) - but I thought...what if I could expand them some? Not all games have social constraints like Wealth, Status, etc. and for those games it doesn't make sense to use the regular rules. http://www.ravensnpennies.com/2014/12/gurps101-barter-and-trade.html#.VI_YhivF8ZM