Authentic battery stores

I visited  one of the hardware store in nehru place new delhi by the name "RX INFOTECH" provided by the dell website in their list of stores. i asked for the  9 cell battery fr my system studio 1558. as per the dell customer care the battery costs 4500/-. those guys are selling at 5900/-. on asking y such a difference, they immediately shot bak saying "then go buy where its costing u 4500" !! i mean wats the point of going to such authenticated stores wen these idiots dnt even know how to talk or give a reason fr such a difference!! eventually some other person told us it was becoz of the warranty thing that they were giving 1 yr warranty and that the dell company's direct order warranty battery has only 3 months... there is no point going directly to such stores.