k I am just going to lay this here and see how you guys feel about this.
Remember the Diablo 3 auction house? There an actual real money aspect to it and you had the gold side for bidding and on the other side you had real currency for bidding. People could sell any gear. What if raiding gear (all gear) was BOE and you could sell anything on either side of the market so to speak. It would bind on equip however (unlike D3) Imagine someone selling mythic gear, legendaries, hard to get gears...for real money...that would/may be a real shot to economy...hell that would be a game in itself.
Many different options to start this up with. Many people loved it in D3 and many people also hated it. Perhaps it could be done better with in WoW, I think it might be interesting to discuss.