Cards in the $ 15 to $ 20 range are widely available . ( Make sure you get the right size : the latest-generation iPhones , for example , use nano SIM cards , not micro SIM . )
15至20美元的SIM卡很多地方都有卖(一定要买对尺寸:比如,最新一代iPhone用的纳米SIM卡,而不是微型SIM卡)。