I was really looking forward to trying these - my wife brought me a 7 ounce bag of 100% Kona when she went to Hawaii last month, and I got the Amazon deal for two of these and a twelve-ounce bag of coffee. Since most of the Kona blends on the market are only 10% Kona, I figured a 7/12 ratio of Kona to regular would yield a pretty good tasting cup.
And it wasn't bad, but nowhere near as good as the Green Mountain Double Black Diamond cups that have been my absolute favorite so far. I'm going to try playing with both the amount of coffee I use (I only filled it about two-thirds full for my test cup) and the ratio of Kona to regular and see if I can get a better tasting cup, but so far I'm not seeing these as a viable alternative to buying the real thing.
I'm sold on the convenience of K-Cup coffee, so I don't mind paying a little extra to have a great tasting cup. If you're looking for cheap rather than convenient, K-Cups probably aren't for you anyway. You usually don't buy a Keurig machine to save money - you buy it because it's fast and convenient.