It's no secret that phones generally cost more in the UK than the US, but when you actually compare the cost of buying the iPhone 6S and iPhone 6S Plus outright it's quite surprising how much cheaper it is in the States.Research carried out by Voucherbox found that the cheapest deals for the iPhone 6S and iPhone 6S Plus were all in the US, with the UK featuring in the top three most expensive countries for both models.