First, you will need a thermostat to regulate the under-tank heater.
Second, if you're using just a 28-qt tub get one with the latching handles so the lid stays on securely. Snakes are strong and can push lids up from the inside.
Finally, if you are purchasing a critter online I wrote up a how-to-not-get-ripped-off post a while back. Pay particular attention to the portion about researching the seller.
http://ball-pythons.net/forums/showt...g-Herps-Online