Hi Jerry,
I bought a convenience-store drink cooler and had the vendor install some sort of safety valve that would kill the system if temps got too out of whack. I was told that was needed to utilize it at brumation temps that were warmer than the temps you'd keep drinks chilled at.
I ran it empty, to see how it would work, before putting snakes in it. On the 2nd day or so i found temps of about 100 inside and humidity steaming the glass doors. We did some re-wiring. I eventually got it working but had to leave the doors cracked an inch or so to control the humidity. For me, at that time, using the (costly) equipment i got, it wasn't a very satisfactory (ie reliable) solution for a rare collection. I used it just that one year.
If you do use something like a wine cooler, my advice would be to run it for weeks keeping a close eye on temps and humidity, before putting anything valuable in it. Someone else's observation here that you need some sort of fresh air supply also sounds like good advice. Good luck!