you can get relays from grainger or any refrigeration parts house.
are you looking for NO, NC, latch on or without the latch-on?
I would expect that the relays used are GE RR-7 or RR-9 relays. I'd be really surprised to see those at a refrigeration parts house. Electrical distributors who handle GE lighting controls should have them, though. There are commonly used (even today) in commercial lighting systems.