I'm no expert but...
I have also been looking into getting a thermostat, b/c I just don't feel confident when I leave my apartment. The temps are just so dependent on many different factors that are out of my control once I leave (windows, doors, fans...), with the big one being me not being around to make adjusts to the rheo when needed. Anyways, I have been doing some research on here and on fauna and there seem to be quite a few stories of animals getting cooked due to thermostat malfunctions with the less expensive models. Now, I am sure many people have the $30 type thermostats and have never had a problem, but going with something more expensive (Helix, BAH Proportional, etc) gives greater accuracy and reliability. I know it is more money (~$100) but I would rather spend a little extra now and not cook my $80 animal and have to spend $80 more to get another. Besides, that thermostat can be used for multiple set-ups if/when I get more snakes. When I leave my apartment I want to feel safe knowing that my setup isn't going to malfunction. Now this is all just MY OPINION. Hopefully this helps!