According to Fat Dan on twitter, Mosley vs. Mayorga II will be $49.95 on PPV while Mares vs. Santa Cruz on the same night in the same City will be free to air.

Dan Rafael ‏@danrafaelespn 6 hrs6 hours ago
I'm told 8/29 Mosley-Mayorga 2 is at The Forum in Inglewood, $49.95 PPV. Will be hard sell w/ SantaCruz-Mares same night on ESPN at Staples.