Budget smartphone amateurs are in luck, as both Walmart and Best Buy have a special offer for the Microsoft Lumia 640.

The handset comes bundled with AT&T's GoPhone pre-paid plan, and can be bought for only $29.99 from the two retailing partners. Microsoft added value to the special offer by promising that Windows 10 Mobile will land on the device.

Looking at the specs of the Lumia 640, we see a 5-inch LCD screen capable of displaying 720 x 1,280p HD resolution. The pixel density of 294ppi will be put to good use by the Adreno 305 GPU.

Processing power comes from a Snapdragon 400 SoC, which gets backed by 1 GB of RAM.

The standard storage capacity is of 8 GB, but thanks to an existing microSD slot, users can upgrade their storage with up to 128 GB.

The camera combo contains an 8-megapixel rear camera unit and a 0.9 megapixel selfie snapper. Users can also use the frontal camera for video chats, should they want to.

The handset uses a 2,500mAh battery to keep running, and the OS is Windows Phone 8.1 out of the box.

About that GoPhone plan AT&T so magnanimously offers, it has three variants. Each of the three plans brings unlimited texting and voice calls, alongside endless messaging to Canada, Mexico and a long list of more than 100 countries.

With the $30 per month option, you unlock the possibility to purchase 100 MB of data for $5.

The $45 per month service ($40 with self-refill) delivers rollover minutes alongside 2 GB of data.

The largest, most expensive plan is costs $60 per month (or $55 with auto refill). It lands with rollover minutes, 5 GB of data as well as free talk and text from the United States to both Mexico and Canada and free text in Canada and Mexico.

It should be mentioned that the Microsoft Lumia 640 for $29.99 is a price-cut of approximately 50% from the standard price of the handset at both Best Buy and Walmart. This marketing strategy might have something to do with the recently launched Microsoft Lumia 650, which is another powerful and (almost as) affordable device.