I'm residing outside the US, where iPhones cost a lot more and the new models are available 2-3 months after the release day. I use that 2-3 months gap to buy

I'm residing outside the US, where iPhones cost a lot more and the new models are available 2-3 months after the release day. I use that 2-3 months gap to buy my new phone abroad and sell my old phone to somebody while there's a demand. I recently upgraded to iPhone6 and sold my iPhone 5 for ~$400 (USD), so essentially I paid $300 for the new phone.