This can be a pricey thing to do, but Home Depot has 50 count LED light sets for $1.98 per box. These are equivalent in length and brightness to 100 count sets of regular lights, so the price was phenomenal.
The money savings:
Regular lights cost 9 cents to run an hour and the LED Christmas lights only cost 1.5 cents to run an hour. Assume we have 6 strands of lights and we run those lights 5 hours a day for about 30 days in December. The result:
LED Christmas Lights: $.00152 x 6 strands x 5 hours x 30 days = $1.37
Regular Christmas Lights: $.00912 x 6 strands x 5 hours x 30 days = $8.21We have more than 6 strands going so I think we'll notice a difference this month on energy costs. Other benefits include them staying cool to the touch (no worries about hot bulbs and animals or babies), the ability to run them longer each day, and that you can connect up to 87 sets without blowing a fuse. Outside we can get about 5 of the regular sets connected before we have a Clark Griswold style catastrophe.