Bundling product and option

Hi there, I have 8 hypnosis mp3's for purchase. I would like to add a purchase two or purchase three option for 10 and 25% discounts respectively...and then the purchaser selects which of the mp3's he or she wants in their bundle. How can I do this?

http://catchthis.ca/clients/imind/imind-store/squeeze-page-home/

Thanks,
Shayne