Family Dollar sells K-Cup filter cups that you can put anything into. Grind your own beans..................
That sort of kills the point of the Keurig. Sure, it costs more, but you are paying for convenience. My wife and I use the Keurig for extra cups if we finish a pot of traditionally drip brewed coffee; or if we want a cup without making a pot; or if we have guests who do not like coffee as strong as what the wife and I drink; or if someone wants a flavored coffee like French vanilla, etc.
I had 2 of those. More trouble than they were worth. I can make 1 cup of coffee with a regular pot too.......or 12. Much more versatile.