I have had very nice fabric fray like crazy and very cheap fabric hold up well.
One of the first quilts I did was made from this gorgeous decorator fabric that I should have used wider seams on. Since I didn't and it is already partially hand quilted (one of many UFOs) I am now very carefully quilting beside the ditch in the sashing catching in each seam allowance so that the likelihood of fraying is reduced. I'm hoping this will take care of the problem. Think this one will end up as a display only quilt anyway.