Heat tape isn't really expensive. Reptile Basics will wire it for you free of charge too! It's the thermostat that gets youI am pretty new here, but I've read up on some less expensive thermostats if money is a big issue - amazon.com has a Hydrofarm thermostat that I've read reviews on saying it works well for their reptile set up. I got one and am currently testing it out... So far, so good. As for a human heating pad, most of them have auto-off timers which leaves you worrying over turning it back on all the time. I personally used one only in an emergency situation, as we got a snake while traveling and I needed a way to keep her temps up just until we got her home. I don't think I'd recommend it for long term use... Anyway, that's just my two cents
hopefully there will be others who can give a more experienced standpoint on it!