I ride with one of these -
http://tacticalhid.info/e03

same XM-L T6 driver as that $95 light you linked, but it can run off either a single AA (1.2v) or a 14500 lithium (~3.7v).

it's bright enough for me with a normal AA on high. But it's bright as hell with a 14500

hope that helps, it was about $30, or you could run 3 of them for the same price as that other light, that is the same power.