11x12 inch flexwatt
clips to connect the wire to the flexwatt.
Inexpensive extension cord, cut off the female end and wire to flexwatt
Thermostat to plug flexwatt into.

Start with a locking 15 qt tub for a hatchling and when it grows up switch to a larger tub.
With a 15qt tub you'll want to only put half of it on the heat tape to get your temps appropriate, when you move up to a larger tub the 11x12 inch flexwatt will cover around 1/3 of the tub, perfect for larger tubs too.