Wow, that is a lot of old equipment. Every arcade I have been to in a long time that has any old equipment has it on purpose and they fix it when it breaks down. I find it amazing that the operator didn't know that even a dead Tempest is worth $500.
Tempest is a great game, I only know of one of them in my area that is still on location, City Museum in St. Louis has one along with a Ms. Pac, a Sunset Riders and a BUNCH of EM stuff (they also had Bad Dudes and Centipede but both of those appeared to be dead when I was there).