That, along with, "it's just a fuse", or "its just a quick fix". Don't believe stuff like that. There's probably some some other things going on. There usually are.
I usually sink about $350-$600 into repairing & refurbishing a game. It will be more if you buy brand new boards and displays.
Personally, I think $800 is too much for that game without showing that it can boot and play.