I would happily trade items from my inventory for things in the clan store I actually need. 

One of my legendary melee offense gems in exchange for 800 scrolls? Sure thing!!

Then the gem is bought from the clan store by one of my guys as he trades in 1000 vip boosts that he doesn't need. 

If everything was given a point value, we could buy, sell and trade in the clan store. To keep it fair, items traded or sold back to the store could be given a holding period (8 or 12hours, etc) before anyone else could buy or trade for it. That way its not dominated by people trying to hook specific members up with certain items right before battle.