If you have a source of tukey or goos wings and the knack to do it yourself, they are fairly easy to split the quill with a razor knife. Then I use a Jo-Jan straight clamp with extra clamps to hold thye feather tight. I can trim a bit more with the knife if necessary and then sand the feather with a block of 150 grit.
I can make a feather from quill to fletch in less than two minute. They glue on as well as commercal grinds.
I also buy a lot of Trueflight and Gateway by the 100 bag in standard colors. But the naturals are getting very hard to find and spendy too!