JemJem offers the refurbished Apple iPhone 6s 128GB 4G LTE Smartphone for T-Mobile in Silver for $384.99. Coupon code "DISCOVER" drops that to $369.99. With free shipping, that's $80 under the lowest price we could find for a new unit.

Note: A 90-day JemJem warranty applies. Don't have T-Mobile? MyWit via eBay offers an unlocked unit in Space Gray for the same price.