Try Herpstat direct, They show most in stock now....
I have a Herstat HP to run my oil filled heater (no longer made) and a pair of Herpstat 2 Red (also no longer made)
Got all 3 direct for the same price as aftermarket / They will put them on sale every now and then.
https://www.spyderrobotics.com/index...=index&cPath=1