I think it depends alot on the condition of the playfield;
Shit payfield $2500- new decals added, new plastics added plus a tidy up gives you a $3500 machine.
Good payfield $3000ish- new decals added, new plastics added plus a tidy up gives you a $4000 to $4500 machine. Pimp it up with LEDs, plane mods, arc mod etc. You'd have youself a very nice pin worth $5k easy.
Cheers Gav