Just taking my cue from the title of this article, the best way to limit the cost of a data plan is to not have one. Go with a phone only plan with your carrier and use WiFi for data and it saves alot of money. I don't know if its possible on an iPhone but I've done it on a BlackBerry and a Windows Phone, and I have family members that do it on Android . . . Why pay for internet access twice (home router and data plan)? WiFi is everywhere already and still growing.