LED's are the way to go. I have several battery powered sets that I got a couple of years ago at the end of Christmas clearance sale. I believe they came from Hobby Lobby or Big Lots. On two sets I hacked the battery pack so I could hook them up to the wiring in my truck. I have a lighted Christmas wreath mounted in the grill for the holidays.
What would be fun would be to hook a set up to a dynohub...
Aaron