Thanks. Actually I was thinking of spending about $50 initially for 20-30 pieces, just to see what type of reactions I get after handing them out. I probably could give out at least one on each evening commute. After a month, if the response is positive, I could start looking into getting backing from an advocacy group.

Those eBay units look good, but they don't come with batteries. I actually have one of those generic units on one of my bikes, and it's worked fine for years.