I tried placing an order with Digital Heroes for one binder today...and when my card wouldn't be accepted as a payment when I went to checkout, I made a phone call. Basically, I was told that you had to order a binder AND a box in order for it to work. I ended the call there and thought about it for a few hours...and I just found out that the binders are now sold out. :-/
Called Digital Heroes again and asked how many boxes they had left to sell and the person on the phone said just 5. Upon hearing that, I had to place an order for one...which is now the maximum you can buy. He also said that the demand is much higher than they expected and that they sold over 50 binders just this morning.