I have a 3GS and want to upgrade, I was thinking about getting a 4S from best buy for $50, or is that a bad idea? I suppose I could get the 5 for $150 but including tax and the $36 att charge it starts adding up. By the way I got my 3GS when the 4 was already out, and the 4S was just around the corner so I'm not too worried about having the latest thing.