I am looking to buy a refurbished iPhone 6 Plus to use for text-messaging development and demos of mobile-friendly websites that I build. I figure having an iPhone 6 Plus would be best because it is larger and being an iPhone might make me look more sophisticated to potential customers. 1.) What is a fair price to pay for such a phone? 2.) How can I be reassured it will run on Cricket or possibly AT&T's netowrk? 3.) What can I do to avoid being scammed? 4.) Any known defects or issues that might cause me to buy a lemon? 5.) Never having owned a smart phone before, any other risks or gotchas I should know about before buying a non-new iPhone 6 Plus off the Internet? Thanks.