They also have a new economical line the ez 1 and ez2 you might want to look at if the herpstat 2 is too much. It doesn't have a digital display so that might not be what you want but it is much cheaper and still a proportional thermostat.
Do you know if the economical line Herpstats are identical to the regular ones with the one exception being the digital display? Or are there other differences?