Why not suggest it to Admin? Seems like a good idea BUT the problem comes if people swop bits and one party is not happy and it gets nasty. Don't go on other horsey forums so not sure how they work over there
I asked admin this ages ago, as part of their website agreement (whoever they have their website from) they cannot sell, and as swapping would incur money (they said this...not me!) they can't allow it. There is nothing stopping someone setting up a mini site to do this, but I did look into it and at the time there was a member doing a swap bit on their website.
again, will see what I can do....