The best part about EMs is that they often need very little in terms of parts. Maybe a spring or something. The Pinball Resource is a great vendor for older parts. EMs can often be a little rough condition wise but if it plays good it is worth it in my opinion. You can see the condition before you buy so you should be comfortable with the purchase.
http://www.pinrepair.com/em/index.htm
This is a great resource!