I have tried battery operated vise lights and have not been pleased with their performance. Light is not really bright enough and batteries do not last long. I hope someone knows of one that you can get, but, I never found any that I was pleased with. Maybe you can try out some of the battery operated lights that fit on the bill of your ball cap and adjust it so it shines down on your vise and fly. They do provide enough light for hiking back to the access point after a days fishing and they may provide enough for fly tying. I may even try one myself.
Thanks for the post...
Warren
Fly fishing and fly tying are two things that I do, and when I am doing them, they are the only 2 things I think about. They clear my mind.