I was in sears about an hour ago and they were marking down all of their craftsman grinding wheels 50% off. This applied to 4 1/2', 6 and 8 inch wheels. Also buffing wheels and supplies.
The Palm Desert CA location had the masonry grinding wheels on clearance $1.50 or so if I remember correctly. I would have picked them up if they were for metal but I guess they weren't on clearance yet. I did however pick up four buffing wheel & compound sets Item #928650 for $6.47 each (~10 cents more than the HF version AFTER 20% off.) Hopefully they'll be decent enough to polish a set of wheels I have lying around.