A G.E system where the G.E. buys certain skilling resources at certain prices. E.g. Dynamite sold at 80 coins. Would make Raids and other bosses a decent money maker instead of just relying on rare and unique drops. Also, if you want to sell the dynamite at a higher price e.g 90 coins you can only sell to a player as the G.E will have a fixed price. This is mainly for instant sell and ONLY skilling resources work like this.

OR adjust the sell prices of the items to the shop.