I'll just post in here.
My 10w LED lights draw .86A each. 950 Lumens, and are about 3x as bright as stock lights, or traditional Trail Tech lights, and only about $25 each more. They are $99ea, shipped.
You can get an 18ah SLA battery on eBay for about $40 shipped. The 18ah would run two of my lights for approx. 10 and a half hours on a full charge. For most people, that would be an entire weekend trip. My LED's operate on 9-50v, so you may even get a longer than 10.5 hours run time.
http://www.ebay.com/itm/12V-18Ah-Sealed-Lead-Acid-SLA-AGM-Replacement-Battery-/270913680203?pt=US_Batteries&hash=item3f13b6b34b