Free if you ask here and learn to do it yourself. A lot of us like fixing as much as playing.
If you want to be an EM pinball owner it would behove you to learn the basics. Tools to repair most problems on an EM are a switch adjuster, a little file or sandpaper, and your brain. Maybe a jumper wire.
www.pinrepair.com/em is the go to to learn about electromechanical pinball machines