HELP!! I need to change my uromastyx heating to cut down on wattage!!?

To get my uromastyx baskin to 120 degrees in my 55 gallon tank i have had to set up 2 150 watt basking bulbs and a 150 watt ceramic heater. he also has a heating mat that goes under the tank underneath his rock den so he doesn't get really cold when he's hiding out, and of course his uv bulb. My parents are really upset because the electricity bill has gone up to $300. I need to find a way to cut down on his watts for the basking area. Is there a more energy efficient way to achieve this??? The tank is about 21" high i believe, and the baskin is on a cinder block. I need any and all advice on how to make this better so i don't have to get rid of Max or move out of the house!!