I highly suggest that you lower the cost of individual cards and booster packs, not only would it make many people happy, you would make more money, because i doubt that many people pay 50$ for one card, if you lower it to maybe 5-20$ max, 20 being for the best cards, you might actually make some decent money, I love this game, and I have been hooked on it the past few days, just one of my observations
after i kill the last guy on a level, my person dissapears...then inorder to get back to the game, i have to quit then load game...but i dont get achievments