Allow experience from selling/buying on market place with liquidity providing multipliers of said XP of lower prices/higher depending on the supply of such items. To encourage fairer prices for all Pixels players, especially starters who may not have alot of coins, but to also to prevent inflationary market prices.
Futures could be established at an 'Exchange' building allowing guilds and other players to buy 'insurance' or bulk buys of items to avoid impacting starter players on the normal market.