I've yet to find any proper references to this beyond "sources say," usually when it's real sources inside the company are cited -
A 'Google Play' version of the Moto X is coming soon | The Verge
Someone who thinks as I do -
Why the Moto X Google Play edition doesn't make sense
Date unavailable, price unavailable. I suppose it could happen. Might help T-Mo customers if they don't have it by then.
And the mfg cost keeps changing - and I'm not sure that anyone outside of Motorola accounting knows that figure either.