Hola nickkroupa, thanks for your message.
I see it's been a while since I updated here, so here we go: went there with a friend. Explained to the guy(/employee, not actual owner) why the engine is toast. Offered 3K, and got a phone call 15 minutes later that we'd have it for 3.5k. We'd pay within the next couple days and pick up the boat 6 days later.
3 Days later we find out he "sold" it to someone he owed 10K...
So we're screwed plus that other guy is screwed who believed he got a boat worth 10k. He wasn't pleased when we told him what it's really worth and didn't want to sell for so much below what he 'paid" for it.
So for now the deal is off. Who knows what might happen when the owner gets sick and tired of having that boat on his lot, but for now no X-Star for us.
Thanks everybody for your advice, especially 46Chief, you've been of great help!