I was lucky enough to win an auction for rotary blades where the final cost was about $1 a blade.
So I finally decided that it was "Penny Wise, Pound Foolish" to try to squeeze out every last cut from a rotary blade or sewing needle. when you figure that the fabric alone for a quilt can easily exceeding $100 then an investment of a dollar or two to ensure that every goes smoothly, seemed worth it to me.
This is my personal opinion. I know others feel otherwise. But I tend to get frustrated when the blade doesn't want to cut or cut all the way though. So it is cheaper for me to just replace them and make things easier.