I usually get at least a couple of weeks to a set of batteries. I just run cheap alkaline batteries...My wife does a really good job of finding stuff cheap. She watches the clearance racks at local stores, and picks up stuff when it is silly cheap. She bought several mega-packs of AA batteries on 'crazy dayz'. 2 bucks a pack, 40 batteries per pack...I'm set for the year[8D].
I think she got them at Menards building center. They are 'North Tech' brand, and cheap to begin with, but they work just fine.(mercury and cadmium free, for a bonus[sm=thumbup.gif]...you know...'save what's left of our planet', and all that...)