Gotta say RIGED is into something here. Vegas are sold out everywhere and I don't think the holidays can account for this. Someone, somewhere has figured out a way to tap into their mining potential of these cards. How's the diff growth looking on ETH and XMR?
Its a combination of AMD discontinuing the Vega reference design (shifting to custom boards) and VERY high demand because the Vegas are really profitable for minging.... For gaming they are mediocre and you are better off buying at 1080 or 1070 Ti for the same or even lower price.
From what I understand, North America is pretty much sold out and here in Europe, they are very hard to find as well.