I voted $3k-$5k because I think at that price you can't lose. Once you see it, it may actually be worth $5-$7, but I don't think I would risk more than that no matter what (at least at this stage).
It is possible that once you see it, it might become worth more, but at this point, you have to assume the engine is only worth it's core value, and everything else is parts. Plus, all the time you will spend dissembling the plane to sell the individual parts. In the end, you want to at least break even, but hopefully make a little money on it for your time.
