Microsoft's lower-mid-range Lumia 640 certainly impressed us when we reviewed it earlier this year, thanks to its beautiful HD display and solid performance, and a pretty decent camera too. And the low-cost Windows Phone has become even more appealing as its price has continued to fall in recent months.

Until recently, you could grab the 640 for $59.99 off-contract (albeit locked to AT&T) via the Microsoft Store - but it's now on sale there for just $39, making it one of the most affordable smartphones available anywhere in the US.

The Lumia 640's key specs include:

5-inch ClearBlack IPS LCD with HD (1280x720px) resolution and Corning Gorilla Glass 3

Quad-core 1.2GHz Qualcomm Snapdragon 400 processor

1GB RAM

8GB onboard storage (plus microSD support up to 128GB)

Backside illuminated 8MP rear camera with LED flash and 1080p video recording

0.9MP front-facing camera with wide-angle lens and 720p video

Wi-Fi 802.11 b/g/n

Bluetooth 4.0

NFC

Ambient light sensor, accelerometer, proximity sensor, magnetometer and SensorCore

Replaceable 2500mAh battery

141.3 x 72.2 x 8.8mm; 145g

Windows Phone 8.1 Update 2

However, if you're keen to save a few extra bucks, you might want to wait just a few more days. As part of the Black Friday promotions announced by Microsoft last week, you'll be able to pick up the Lumia 640 for just $29.99 from Best Buy from November 26 to 28.

And if you're a fan of Microsoft's mobile devices, there's one more reason to buy the Lumia 640: the company has confirmed that it will be among the first handsets to be upgraded to Windows 10 Mobile.

Source: Microsoft Store via Windows Central