B&H Photo Video had a great deal on the Samsung Galaxy S7 edge - $550. It's now out of stock and it's not clear if it will come back in stock at this price - the promo ends on midnight December 1, new stock is expected in "2-3 days." Note that this is the G935FD version - Exynos chipset, dual-SIM. Walmart has a Galaxy S7 (non-edge) for $550 and this one is in stock too. This is the G930F - Exynos again, though single-SIM. These two support US GSM carriers, but CDMA ones (Verizon, Sprint) are a no-go. You could wait until December 7 and snag a Snapdragon 820-powered Galaxy S7 from...
Source: http://www.gsmarena.com/galaxy_s7_and_s7_edge_deals_in_the_us_starting_at_550-news-21902.php
