Microsoft now sells the Yezz Billy 4.7 Windows Phone 8.1 handset in the US
Available in the US via Microsoft Store, the Yezz Billy 4.7 costs $199.99 - no contract required. We’re obviously not dealing with a high-end device here, but that doesn’t mean the Billy 4.7 doesn’t come with most of the software features that more expensive WP 8.1 devices have (including Cortana). On the hardware side, the new handset offers a 4.7-inch IPS display with 720 x 1280 pixels, an 8 MP rear camera, quad-core 1.2 GHz Snapdragon 200 processor, 1 GB of RAM, and 8 GB of expandable storage space. The smartphone’s got dual SIM capabilities, and is only 7.2 mm thin.
You can get the Yezz Billy 4.7 via the source link below, though you should also consider looking at other Windows Phone 8.1 handsets that are cheaper - including the Nokia Lumia 635.