My worst would have to be Strikes and Spares years ago when I did not know anything about pinball. The playfield was down to wood. I thought it was easy to fix (decals) and I was wrong.
Paid $500 for it and after painting it it still looks like ass.
My BEST deal may be TOTAN. Bought right off route for $2700 last year. Was covered in dust, selenoid was fried and looked rough. After I got it home and started cleaning it I realized it was mint. Cab 100%, back box, playfield 100%. Put about $500 in LED's, gold legs, new coin door.
Looks like it came out of the factory now.