Depending on the style of collar you presently have it's quite easy to modify the collar for a smooth look. In my case, I cut the nub off that housed the pin where the shifter arm pivoted. I then smoothed the collar where the cut was made with a grinder and rolled sand cloth, by sandwiching the collar in vise jaws. Next I "backed" the remaining hole on the inside of the collar with curve-cut styrofoam making sure the arc of the foam was a bit greater than the arc of the collar to leave a space under the inside arc of the collar. Remove the inner foam by hand or with nail polish remover. I then filled the hole and space between the foam and collar with body filler. After setting I repeated the sand cloth step making sure the cloth wrapped around the collar to get a smooth and perfectly rounded fill. After painting, you could not tell where the work had been performed. You can actually turn this area of the collar to the bottom when you remount the collar. Not knowing what your collar originally looked like, I cannot say if this will solve your problem and save you some cash.
