This is the lowest price I have seen for new iphone 6 ans 6 plus.
Looks like bestbuy is clearing the stocks for iphone7 or iphone 6SE, whatever they apple decides to call it.
The offers for both AT&T and sprint you need to choose unactivated to get the lowest price.
and if you activate it on AT&T then you can also get $200 bestbuy gift card making it the awesome deal.
hope it helps