head light only solution: Sanyo dynamo hub $50 +shipping. B&M Lyt plus $46 +shipping. +spokes +labor if reusing a rim. This is about as cheap as it gets for dynamo hub lighting. +spokes +labor if reusing a rim. The Sanyos were going for around $36 but it appears the price has gone up. There are cheaper lights like a Spanninga Micro, and also cheaper lights that do not have a standlight.

You don't have to put the most expensive solution on all your bikes. I have Sanyo, SON, and Sturmey Archer dynamo hubs. I have an Edelux and Spanninga lights. One can also upgrade incrementally if you have more than one bike. My nicer headlights and dynamo hubs gravitate to the nicer bikes as I upgrade. The lesser lights go on lesser bikes.

I like dynamo hubs for many reasons, mostly because they almost always work.