I've noticed some of the higher-end hygrometers/thermometer combos can be prohibitively expensive, one thing you might try checking out is laboratory sources such as:

http://tinyurl.com/7getdgv

There's a bunch of different companies that make for scientific needs, and you can get some good quality equipment for a decent price. Also, I like the ones that have memory storage. Also: cigar shops. Those people are nutty about humidity and temperature in their precious cigar cases.

Thermostats are a bit more varied, but if you look outside the reptile/exotic/pet industry you can find a much wider selection. It may not be perfectly tuned to what you want and require some jury-rigging, depends how much you want to put up with.