if your house temperatures are constant enough, you could set it up with a dimmer.

a dimmer limits the energy-output, so that the UTH, if it runs 24/7, only heats to a level of something like "5 degrees above room temperature" or "10 degrees above room temperature". you need to do test runs and find just the right setting for the dimmer, and it all hinges on the ambient room temperature being constant.

i would not recommend cheap thermostats, they sometimes fail, and when they fail, they can fail in a bad way, so that the UTH runs at 100% and your snake gets burned. good thermostats fail less often, but more importantly, they are designed to fail into the off-state. so when they break, they dont burn your pet, they just switch off.

so a dimmer (set up correctly and with constant room temperature) may be safer than a bad quality thermostat.

i guess in your situation i would go for UTH + dimmer first, and later, when the budget allows it, replace the dimmer with a good thermostat. how is the humidity? heat lamps are quite notorious for ruining humidity, if you have issues with that, a switch to an UTH might allow you to get rid of the heat lamp.