The one pictured is a MAC Tools AR-12. I couldn't find it online nor could I remember the cost but I don't recall it being too expensive. I usually set it to 5 psi when doing a boost leak test and I've never seen it waiver or spike. It's fed right off the air compressor. All of the connectors were purchased at a hardware store, except for the hose on the air tank, which was a pre-made deal from NAPA I think. The end leaks a small bit but I always turn the pressure off right at the tank anyway, no reason to leave the hose pressurized when not in use.
If you're having that many problems with them I'd call a higher end paint shop and see what they use.
