You can get one of each prize every three months. Probably to keep people from doing like in Live Club, getting a bunch to resell. And you can only pick ten prizes total. After that, it probably won't let you play anymore (*coughnewaccountcough*).
I'm intrigued by the cute little aquarium in the pet section. That'll be the second prize after I test this with the notebook sleeve. I could use one. Then some socks, the black water bottle, a spice jar for mom (she loves collecting la creuset), and we'll see what happens from there.