It's nice for people be able to swap walls easily but it's probably going to be the end of FCs Crafting walls for their members' houses or to raise funds. People are selling way below the material cost. The Merchant walls needed a huge amount of materials iirc and the amount of Grand Company Seals needed is usually enormous.
I'm a little sad these walls didn't stay FC exclusives. There's very little for FCs to do together as it is.