I don't buy PPVs any more because I don't like the way they hand out title shots these days and I also find them to be overpriced. (Can't say I've ever been a fan of the PPV model, even tho I used to buy a lot of them.) I'll either stream or download a HQ torrent of the event. There's always one available within 15 min of the event ending.
550,000 buys, tops, is my prediction.