You could do punch cards or stamps like a rewards program. Something like every 5 purchases gets you a 20% discount on anything in the store once you have 5 stamps or 20 bucks off anything in the store that type of thing.
Also my LCS does pack wars once a month to get rid of inventory that's been sitting there & they have good deals on that stuff. They buy pizza & soda & we rip for like 1.5 hours. Then they have a drawing for stuff they can't even give away. Loads of fun.
I still think my boobies thing is a great Idea, but this should help.
THE OFFICIAL BLOWOUT RESIDENT SUPER COLLECTOR OF FRANK THOMAS BASE & UP.
MY PC NFS/NFT: http://www.zistle.com/bboi30/collections/baseball