10-watt NiteRider Road Rat is about $62 plus shipping & handling...
http://aebike.com/page.cfm?PageID=30...ils&sku=LT9000 The main drawback is that the sealed-lead-acid battery may wilt in really cold temperatures. If your area gets below freezing, it might be worth going up to the
Trail Rat version with the NiMH battery, or a
Planet Bike Alias (which has a smartcharger for faster, no-worries charging).