You can buy a filter cup for the Keurig so you can use ground coffee.
This is what I do and there is no waste. I stock up on Starbuck's when it goes on sale and I have a coupon - I'm able to buy each bag for about $4.50 plus you can take the empty bag to a Starbuck's and get a free cup of coffee.
I store the coffee in the freezer.
I have also been able to buy New England coffee for about $1 a bag (on sale and with a coupon) but since I don't care for it, I donate it to a food bank.
If you decide to stay with the 10 cup coffeemaker you can freeze some of the coffee in ice cube trays and use it when you have iced coffee.