This is the cheapest I've found -- but I haven't looked hard.
Cheap Cards
I agree with everyone about the Copag's and assume the other premium decks are just as good.
However, I kind of think it's classy to start a poker game with two brand new decks of cards, to break the seal in front of your guests etc. At these prices, the cost of this 'fun' is less than a buck a poker game. Obviously this is a personal preference.
Also, having children, and several of the old Kem decks that now have somewhere between 49 and 51 cards (Kids are great at losing cards), I think that having cheap cards around to give them a deck whenever needed is great.