alldayzip via eBay offers the Apple Watch Series 4 GPS 40mm Aluminum Sport Smartwatch in several colors (Silver/White pictured) for $389 with free shipping. That's the lowest price we could find by $152 and the first drop we've seen for this model. Features include:

W3 dual-core processor

324x394 OLED display

16GB internal storage

802.11n wireless, Bluetooth 4.2, and GPS

18-hour battery life

watchOS 5