Unfortunately there's no concrete source, it's all rumours and hearsay from multiple places across the net. We are in the rumor thread, and of course you are right to take anything and everything I say with a generous heaping of salt!
Well, AMD does have a history of completely messing up the prices and coming out with ridiculous prices when they feel they can get away with it.
Remember the HD 7900 cards. AMD priced the HD 7970 at $549!! $549 for a midrange card. It was a nearly $200 price increase over the HD 6970. They had to reduce the price twice to get them to sell. The HD 7970 went from $549 at launch, to $479 after the GTX 680 launched, to $429 in June.
And who can forget the pricing fiasco when Vega Launched. Remember all that confusion with the included games and the price that AMD said was only for a limited number of cards. But, even at the lower price, the cards were still more expensive and worse performing then their Nvidia counterparts. Lets not forget that these cards arrived a year after the Pascal cards too. AMD eventually got drivers sorted that increased performance, but that was months later.
I really hope that AMD gets the launch of these cards right and they don't repeat mistakes of the past.