Cage:
http://www.animalplastics.com/terrestrial/T8/T8.htm
A t8 can last a ball python it's entire life. If you get a baby, be sure to order the divider so you can section the cage and slowly move the divider as it gets bigger.

I'd suggest sliding glass doors, as the swing down doors are made of acrylic and scratch easily.

Depending on your room temperature, you may need more than just heat tape.

If you use heat tape, you MUST have a thermostat.

High end:
http://www.spyderrobotics.com/home/products.html

Cheaper:
http://www.amazon.com/gp/aw/d/B000NZZG3S

It's a great idea to get an infrared temperature gun. Or you can get an Accurite thermometer with probe from Walmart.

They look like these (perhaps a different model)

Place the probe over the hot spot, and place the unit on the cool side.

Also, you will need two identical hides. Do not get the typical half log hides found it pet stores. Ball pythons need snug fitting hides.

This is a great place to ask questions! Welcome to the site!