If we're not doing the chests, actually, I think from post #21 onwards makes a lot of sense. So simple. The fact that OP has the say of whether or not they will accept the trade makes perfect sense. Then it's not a "first come first served" basis because the first one interested in OP's item may not have anything OP wants however, if OP doesn't care that that's the case, OP still then reserves the right to ship out the item to the interested party without expecting anything back or maybe would be happy with a dog biscuit.
That's the simplest way to do it. IMO. Not as exciting as a chest virtual or physical but.. it's something new-ish.