I have a my-k cup I'll use occasionally.
If you're just going by price, staples is a great way to go with their coupon. Bed, Bath, and beyond has the 20% off coupon, any other store like that will have the same.
If you live around a publix they have most 12 packs of k-cups for 6.29 now. There was a coupon in the Sunday paper a few weeks ago for 1.50 off two. It comes out to about .47 a piece and it's the good stuff (Donut Shop; Newman's Own Bold);
I've gotten them for .35 a piece before but it was Folgers. Tasted terrible.