The best thermostats are the Herpstats made by spyder robotics. They are going to run at least $100

Here is their website. I suggest the Herpstat 1

http://spyderrobotics.com/

Next up would be the Ranco thermostat. These aren't as good as the Herpstat but still a good option. They usually run $60-$80

You can get them here:

http://www.reptilebasics.com/ranco-etc-111000-pre-wired

At the bottom end is the hydrofarm thermostat. These are the least accurate and what most consider the cheapest usable thermostat. They run about $30

http://www.amazon.com/gp/aw/d/B000NZZG3S


If she isn't using any of the hides, that might be a sign that they are too big or too small...

This shows the perfect fit for a BP hide. Tight, but with a little wiggle room. They like to be able to touch all of the sides at the same time.