To the OP, if the game is cheap and you're up for it, (basic mechanical skills, knows how to use a screwdriver, can solder (or at least learn how to solder)), the price of parts on these games aren't that bad. Probably $200 in parts assuming you have to rebuild the major mechs (flippers, drop targets, pop bumpers and slings, etc.) plus new rubber and new random other parts. If you can put in some time everyday to learn something new everyday, in time you'll have the game cleaned, resetting properly and eventually playing properly. the process itself can be very rewarding. The playability of the game is a another kind of reward. Make sure it's not missing any parts. You'll have to acquire a schematic and learn how to read it, even if you can stumble your way through (like me).
if you buy it, and after a time, don't feel that you can get a grasp of getting an EM running, then you could just as easily sell it. I normally wouldn't recommend buying a project EM as a first pinball machine, but if it's cheap, then go for it. If you can get a working 1 player game, that is probably a bit easier to start off with, then you can ease into tweaking and repairs.
Pinside FWIW can be a very good place to learn everything you need to know about reviving and maintaining games. In that regard, you couldn't ask for a better community. We all gotta start somewhere.