I just tried a K-cup alternative and am quite pleased. Cameron's coffee now produces a K-cup alternative that fits Keurig machines (and compatibles). The cups are different than a K-cup, really just a plastic mesh hanging below a foil disc similar to the K-cup.
The Cameron's cups are shorter, so they don't puncture at the bottom like a regular K-cup, but they work well and the flavor has been quite good. One down side is that they don't fit in the K-cup racks, so I tend to keep these in the box until needed. I thought I'd give them a try out of curiosity, since they were a bit less costly.
My guess is that Cameron's worked really hard to avoid the licensing expenses related to the K-cup.