if you are going to get 2 boats 2 paddles 2 sprayskirts 2 helmets 2 lifejackets 1 drysuit 1 wetsuit and a throw bag with a roof rack and straps. i'd say make sure it all fits well and you are not too big for the boats, helmets, pfds, i would wet test the dry suit before you trade but I think without looking at the gear it could be worth 1500-2000$ total more on the 1500 side.
This will depend on weather or not you want to get rid of the downhill bike. If it were a 2010 yeti, you should know better, if it is an iron horse or kona, i'd say you are both getting a good deal.
gear value 1500$ in great shape, what kind of bike?