Amazon recently offered Samsung Galaxy S6 for $399.99, but it was sold out very quickly.
Fortunately there is another way to get black 32GB version in the US for a similar price.
The offer includes free shipping in the B&H online shop and the order should arrive in up to 3 days, also in particular promotion, you can receive an additional Samsung BP3100, the portable battery charger with capacity of 3100mAh, which will provide power for the phones battery when you will be running low.
On eBay, you can buy the Galaxy S6 for ten dollars less and with free shipping, but in this case without a portable charger.