64gb[walmart.com] available in gold, rose gold, and silver $549.
16gb[walmart.com] available in rose gold, silver, and space gray $499.99.
Phones should be in the warranty period as they haven't been out longer than a year, but I've had success sending apple the invoice and having them extend the warranty period on iPads (not sure about iPhones).
Note: On the webpage, it states that the manufacturer is generic. I'm not sure if there's any replica iphone 6s', but the phone is sold by walmart.com directly, so they should be authentic. I'd record a video of unboxing the phone and making sure everything is okay, or pick it up in-store and open it in front of an employee as proof.