I'll plug my recent purchase(s)
http://www.bicyclelights.com
I've been very happy with them, both the handlebar and helmet system, which I got for <$100, including shipping. I got the NiCd system, but I can upgrade to NiMH just by buying the battery (~$50).
Run time has been as published. Build construction is great.
He often sells through EBay at a discount
http://cgi6.ebay.com/ws/eBayISAPI.dl...ort=3&since=-1