craftgrrl | Yet another marble magnet question...

Hullo Craftgrrls!
So I am hopping on the marble magnet bandwagon--what a FUN idea and just in time for Christmas!! I am recently rediscovering my crafty side, I forgot how much fun it is!!
My question is--is there someplace where you can buy just blank tins? I am in the DC Metro area so if anyone knows of any local places--or even national chains like Micheals, Jo-Ann, etc.
I bought a hole-punch but I goofed and got like the teeny tiny size. Whoops! But I can definitely see how it makes the process easier...
Thanks in advance and keep on crafting!!