I'd gladly pay $250 for a fully working, complete (monitor, coin door, control panel, marquee, bezel all present), restorable Galaga machine. As long as the cabinet has no water damage and is structurally sound, I'd say go for it. If he's planning on applying any new art, I'd consider it an added bonus and have him just give it to you separately so you can clean/fix up the cabinet before applying it.