Just move to FV buy and trade all you want. We sometimes have 3 full general channels of people many are selling and buying. It would be easy to make trades. problem solved.
Would be cool if they sold back for coins, at the same approx 10% value they usually do (based on the item they are a mirror of). But you still need to unlock items on the vendor.
Yeah but what would you do with that coin? I recall you having enough coin from TBM to buy everything in the expansion like 50x over.