The K-cup filter baskets suck. I gave mine away. $14 for the brewer-basket plus shipping, $10 for a 2-pak of extra filters so I wouldn't have to wash it out for two cups in a row (actually I was convinced in advance and bought 2 paks of these), and it never worked normally for me.
The convenience of K-Cups is a great cup of coffee in 30 seconds. Once you figure in fussing with the K-Cup filter, putting coffee in it, putting it in the basket, screwing on the cap, oh, and prying out your regular K-Cup holder so you can snap the filter asket in there, making sure you have the right amount of coffee in the basket so the coffee brews correctly (this was a problem for me), then when you're done, the filter needs to be dumped and the grounds scrubbed out of it under running water.
If you want to use your own grounds get a pod brewer and use #2 T-Sacs for the filters.
If you only have a Keurig, you can get used to the routine of using this gizmo if you'd rather do that than buy K-Cups. I got grounds in my coffee, watery coffee from not filling it full enough, REAL watery coffee from filling it too full, and just plain did not like it.
I love my K-Cups, and I love my pods, and I love my T-Sacs!!! I do have to order all my coffee online, though.
Linens and Things carries a limited selection of K-Cups
I have had good success with the Brew cups you put your own coffee in. You just have to play around with it to get the right grind and amount to get a good cup.