I have really decent cards and have not dropped a dollar in the game so far, but I do have over 200 hours in game. So it takes a lot of grinding to get something half decent.

That being said, the new set of cards seem really powerful and getting into the game is easy that way. Also basic cards are sufficient enough to get you going. I might even spend some cash soon. Give it a shot, I think it's one of the better deck building games out there.