Many years ago I bought 9 machinces from a Pizza place for $1000.00.
Space invaders
Embryon
Firepower
Silverball Mania
Haunted House
Mr. & Mrs Pac Man
Gorgar
Devil's Dare
Black Knight
Not bad to get them for $111.00 a piece. And they all worked. (A couple needed minor fixing.)Still have the HH.
I also bought a mint condition T Zone from a friend for $700.00 but did not have the room for it at the time. It was stored for me untill pick up. A long time went by and my friend needed to get it out of his shop so I sold it back to him for the same price so he could sell it to someone else. Which he did and the new buyer still has it and I am still kicking myself for my extreme stupidity. If I had only known.