Regardless of the merits / value of the Budapest Tourist Cards , I wouldn't try to book it online following my experience in February this year
I tried booking them (2) prior to a trip, but the transaction failed to complete properly. Consequently I did not receive a booking reference number to physically collect the cards on arrival at the airport.
I assumed the transaction had failed and did not retry. I then did without the Cards for our weekend stay. On returning home I found my credit card had been charged with £45. Repeated emailings to the Budapest Tourist Office have not resulted in the promised refund actually happening. I suggest you do not risk booking these online (despite the savings)