As Cebs mentions and I only realised today - the Mask covers are not variants, they are the normal covers and you should pay cover price for them. I just paid £2.20 for my Catwoman.
I had thought that the Masks were variants, and so thats why I dropped £25 on Batman and Batgirl. Annoying yes, as I had already got Batman 13 in my pull list ready to grab, but Batgirl looks to be sold out EVERYWHERE, and if you want it, then you got to pay for it.
That 13 variant looks nice, and is hovering at £15 on ebay, but no one in UK with one to buy outright. Economic hot back to me and my sub is updated, I have dropped that variants eek as I will be buying £30ish of comics that I dont normally buy anyway, and knowing me, I will end up buying the trades of 1-12 for BatGirl, Catwoman, and the other issues to make up the whole storylines leading up to DotF.
Nice like the Joker he looks suitably creepy
Really not sold on Catwoman though, that said I don't like her as a character anyway so not fussed if I have to wait till the 2nd print run but would be nice to have them all as masks