Prism, you are so right about fabric that you no longer like. I was in the same boat. I gifted a whole lot and then found some great pieces I've sold on Ebay. Nothing is more unappealing to me than using a fabric I don't like and in reality I won't use it. Quilting is so much more enjoyable when I have fabric I absolutely love.
I don't know about sheets. I do know they sell them separately in various places. I've never worked with them but many others have.
We used to love flannel sheets but no longer do so I'm going to use some of my flat sheets for backings on some if it calls for flannel.
Yes, it's an expensive hobby but so rewarding.