I too use D'Addario strings and they do last over a month for me. I'm not gigging at the moment but we rehearse once a week for three hours and I play an hour or so a day. I've tried the Snake Oil Brand strings among others like DR's and GHS but always go back to the D'Addario's as I find they give me the tone I prefer and last longer than most. I do like Ernie Balls on strats but they don't last as long.
+1 They will be selling the Kaman brands in Kmart, Walmart, PriceClub to expand the retail exposure of the brands after they kill the quality. You know what Ray say's about Kmart.