How to get a cheap, cheap iPhone 5S for under $300 from a friend or relative

It's a little trickier to find a cheap iPhone right now, but that's the beauty of Apple.A new iPhone can be had for as little as $300 or more, and that's a steal for a smartphone that can't be had at a Best Buy or Target store.But with the advent of China's "unlimited" iPhone pricing, it's a much more difficult proposition to find an iPhone that's affordable.Here's how to find the cheapest iPhone ...