You can get a 12-pack of NiMH AA 2700 mAH batteries from BatterySpace for $16 and shipping, so if the eBay guy is charging shipping on top of $1.50 a cell, walk away. Lately I've seen a HECK of a lot of stuff on ebay going for OVER list price. Don't assume you're getting a deal.

I bought that Malibu light and never wound up using it. It's kind of clunky and big and it looks like the front would rattle off when riding. I'd get an Optronics if I was going to do DIY halogen, and wasn't going to go for the traditional plumbing fittings I did last time.