Microsoft has removed the licensing fees for Windows Phone 8.1, and at the same time, has lifted hardware requirements except for the use of a Qualcomm processor. Microsoft also launched a portal site recently, designed for wannabe low-cost Windows Phone producers.
As far as BLU's Windows Phone model is concerned, the design resembles the BLU Dash 5.0 which can be purchased for $121 from Amazon. That device offers a 5 inch LCD screen with resolution of 480 x 854, powered by a dual-core 1.3GHz processor with 512MB of RAM. The unnamed Windows Phone model might not share the same specs as the Dash 5.0, but keep in mind that it will be competition for the Nokia Lumia 520, not the Nokia Lumia 1520.
source: BLU via WMPoweruser