Before buying any machine, make sure it is one you are truly interested in and ideally have played before. Don't buy your first machine just because it is close and the price is within your budget. Pinball machines are everywhere but may require just a little bit of patience to find what you're looking for. I suggest going to the Louisville Expo this weekend to play everything you can and maybe even purchase a machine there. However, you need to do some research, even a quick post on pinside, to do price checks. There are some sellers there that have higher prices that run retail businesses and have overhead to cover which is fine but your situation sounds like you'd prefer to pay less and do your own work and maintenance. There will be some fair prices there as well from individuals and hobbyists.

John Wart is very close to you in Columbus and can fix any of your pcb issues at a very reasonable price. He can also help with any restoration you may be looking at.

I personally don't think a non-working scorpion with bad back glass is worth $350 and I would doubt that anyone bids on it. I think it's worth about $200 from what I see. Even working, it's probably a $400-$500 machine. Here's the ebay link for the Scorpion...
ebay.com link: Williams Scorpion Pinball Machine Project