What should I offer for a recently captured Jaguar?

So my friend who owns his own retro game shop got a Jauar in from the wild. He told me to make him an offer. He's got machine two controlers, an orginal video cable but only generic power supply he's got a few games but the ones I want are tempest, wolfenstein, and alien vs preadetor all games are loose carts. I see some prices on eBay can be high while thrift shopping it can be dirt cheap  but I do not want to troll forever. The only thing I have to offer is a Mario RPG SNES cart and a coleco keyboard  so I know cash will play into it.
Thanks, a 5200 fanboy who is looking to upgrade.