One of my favourite stores uses a punch card system, but the keep the cards in a file by the till for you. You don't have to punch your own card, either; I don't shop there enough to want my own card, so I just have them punch my Mom's card when I'm there.
I would never pay for a punch card, unless I knew I would shop there enough to make it worthwhile. My purse is full of half-filled punch cards that are useless because the programs ended before I could redeem my card.