For Prime members only, Amazon offers the Unlocked Motorola Moto G G4 32GB Android Phone with Offers and Ads in Black for $139.99 with free shipping. That's the lowest total price we could find by $50. (For further comparison, we saw the version without offers and ads for $40 more in July.) It features a Qualcomm Snapdragon 617 1.5GHz octa-core processor, 5.5" 1920x1080 touchscreen, 2GB RAM, 16GB storage, 802.11n wireless, Bluetooth 4.2 LE, 13-megapixel rear-facing camera, 5-megapixel front-facing camera, and Android 6.0 OS (Marshmallow).
Update: Note that this item is temporarily out of stock, but can still be ordered at this price for delivery when available.