This seems to be a popular inexpensive option for a thermometer/hygrometer.
http://mobile.walmart.com/ip/Acu-Rit...mometer/896347
I wanted to say, the premade kits at the pet store..I thought those were great until I realized I was buying different things from different places. If only they would put absolutely necessary things in them. That would be fantastic.
Best of luck with your snake!!