did he state on the auction that they were BOTH working in perfect order ?
if yes you can go through ebay themselves.
if no it was your responsibility to inspect the items on his premises and i take it that was not the case so it's going to be hard to negotiate a return.
Or go with what bouncer says. ( not recomended but if all else fails why not have a nice big assault bill on your hands to pay the guy even more of your hard earned money).
i feel for you as scams are widespread everywhere that's why i love the system here on AVF much safer. ( mods i'll accept my fiver later

)
I wish you good luck though i hope you resolve it.