Amazon has the Shimano dynohub for $125. Then you have to build a wheel. You might be able to re-use your rim if it's got 36 holes.

I explored dynohubs in the past, but LEDs and LiPo batteries have really narrowed the gap. In my garage, I've got a super long USB cable that we all use for charging our lights. I've used cheap lights from AliExpress, and they are actually quite durable.