I made a good buy on eBay yesterday. I bought a 12v 7ah SLA rechargeable battery for $3.00 plus $8.00 shipping. I'm going to use it to power some lights I'm getting ready to build for my bike. The light kit is real cool. Here is a link to it: here.
It's made with cheap stuff from Home Depot and for the price you just can't beat it. I'm not going to use the 50 watt light because it can't take the heat (so to speak), but I'm going to use two 20 watt lights instead. When I get it done I will have some pics so you all can see.