I've had my balls for about a year now and have had pretty good success just using a 250 watt infrared bulb (the kind used for brooding baby chicks) suspended from the ceiling over each tank and raising/lowering it depending on the time of year. It gets cold where I live during the winter (~50 degrees in the house) and these lights are powerful enough to provide a good heat gradient in the tank even during the coldest nights. They work well because directly under the light will be the hottest and serves as a basking spot, and the edges of the tank are cooler. The snakes can choose which spot in the tank suits their temperature needs. I check thermometers at least twice a day to ensure that the temperature range is where it should be. The tanks are near windows, so they have natural light for their dark/light cycle. It's worked really well for me and is definitely not as expensive as some of the alternatives.