Let me just say that people do INDEED buy them. I really liked selling the new rare from a fortnight ago for 42.000Ctz.
This is not even so for this games exclusively: New things are almost always ridiculously overpriced... and yet there are enough people willing to pay.
A good estimated development: Commons: down to 200-600 in 4 weeks, uncommons: 900-2250; Rares: 5000-30000. Obviously, THEN, highly depending on the card's power in the game. (note: estimated. While I found that it is genreally fitting, there are always cards that do not fit in)
... and then you see people putting stuff like 10x Ielena on sale or see the prices of Cr... some people are disgusting rich beyond common folk imagination...
Actually, those cards will go even *below* their fair price as they are in the new blood packs and the market will be oversaturated by them in some time. Then again, with that line of thinking we would be living on trees.