If you're looking to stick with the Windows 10 Mobile ecosystem for a bit longer, Microsoft is offering a pretty tempting discount on the Alcatel Idol 4S. The unlocked phone is down to $99 at the Microsoft Store without an included VR headset, which is a cut of $200 from its normal starting price. If you'd prefer to pick up the phone with a VR headset, you can grab that bundle as well for $169 (via MSPU).
The Alcatel Idol 4S comes unlocked with support for GSM bands, so it should work fine with T-Mobile and AT&T. Inside the phone, you'll find a Snapdragon 820 chip, along with 4GB of RAM and a 3,000 mAh battery with Quick Charge 3.0 support. As for the screen, it's a 5.5-inch FHD AMOLED affair. You'll find a fingerprint sensor on board the Idol 4S as well.
Given that Windows 10 Mobile is kind of flailing in the wind right now, this probably isn't the best time to be jumping into the ecosystem. However, if you're an enthusiast, or simply want a fairly cheap backup phone, this represents a pretty solid deal for what we found to be one of the better Windows 10 Mobile phones on the market when it was released.