Well, when cards are "sold out" it means that they aren't printed anymore and can't be found in the packs... But, you can still buy them on the market, if someone is selling them...

But all those cards that I have mentioned (and probably a couple others) are really awesome as they have great stats, and in my opinion, they are cheap atm... But, as there is no more printing of them, their price can go only up (again, in my opinion)...

Just do Music Lessons and that nasty EGO will go down slowly... :)