I bought an iphone 4s unlocked. I currently use it only for wifi at the moment. Im from the usa and in canada at the moment. I had to go back to the usa and also got this phone when ordered on ebay. I did not buy a sim card and dont have one. I would want one once i get back to the usa and thus have a carrier plan while in the usa. I know virgin mobile is the cheapest carrier plan but i didnt buy that iphone b/c if i wanted to use the iphone in canada on a plan, i wouldnt be able to buy a sim card in canada and use it just like that. From what i read, theres basically if i want monthly plan, its tmobile, straight talk or metropcs right? Tmobile is 50 plus tax a month, straight talk is 45 plus tax per month and metropcs is around the same? How much does a sim card cost for each carrier? I see that ebay has tmobile sim card for the iphone4s for like 5 dollars or so. But why does sim card cost lot more for the other 2 carriers? Obviously tmobile would be the best choice out of all of them? Curious about the service of straight talk and metropcs.