How desperate are you? If Staples or Radio Shack has it, it's likely to be really expensive, but they're easy enough to check from the comfort of your Web browser and their B&M stores are pretty ubiquitous (is that an oxymoron?
) I have no clue if Microcenter or Fry's carry cell phone batteries at all, but they might, if either of those is handy... Target, maybe even??
But I have to say, I'm only (very) mildly surprised that Best Buy doesn't carry them at all. Dunno about years ago, but it has seemed to me for quite a while that they carry a
very narrow selection of usually overpriced, high-margin "accessories" for pretty much everything they sell (e.g., they certainly carry plenty of overpriced phone cases, low(er) end earbuds, and mostly mediocre USB chargers.) Not that I really blame them. Except for things I think there's a reasonable chance I might want to return, it doesn't make me buy from them when I can get significantly better prices online or anything, but realistically, competition from e-tailers is making brick & mortar retailing ever more cutthroat every month, so it's only realistic that they're gonna do what they gotta do to maximize profit-per-square-foot, or however they measure that sort of thing...