Sounds like too much fuss than it's worth.That wire cage will be dirty and tough to clean.I'd spend 25$ on a cheap aquarium and cover before I'd rough it.Usually a party bulb will work for heat or a small heating pad just so they can warm up if it's too cold.Maybe just a red fluorescent thats left on most of the time during the winter. I'd stay away from heat rocks they can get too hot for cresties.Of course if your really on a budget get the biggest sterilite container you can afford and poke a lot of holes in it(you'll need good airflow to keep mold down),you can keep it for a quarantine for future use after you buy a real terrarium,don't bother with the expensive substrates,use paper towel, get the temp. and humidity requirements set...