It really is just two categories - cheap thermostats and pricy ones, no range in between. This is because the cheap ones just turn the heating source on or off when it reaches the desired temp or drops too much below it while the expensive ones actually ramp the power up and down to keep the temperature consistent. The hydrofarm jumpstart one is generally considered the best in the class of cheap (taylorr provided you a link to this one) while most people prefer the herpstat in the expensive class (both Deborah and Taylorr provided you a link to this). The expensive one is legitimately way, way better. There are some similarly priced thermostats to the herpstats that are also considered good, eg. vivarium electronics' http://www.vivariumelectronics.com/Products.html
I have just ordered two herpstats with two day shipping. In the mean time i have a heatlamp on the ball python and the boa. thank you all for your amazing help and for educating me.