As others have said, the margin on many tools is very small. It took me awhile to realize that in general, 15% off a power tool was something to move on. This conditioning has helped me make quite a few good decisions when I found things at 40% or more off on clearance or in the "blow out" bins. Instead of missing out by waiting to ask someone "is this a good deal?", I snapped them up and am using them still.
In my area, Lowe's and Home Depot do seasonal changes to their displays. Right after, they dump the tools that the workers took out of stock and used. This is where I picked up my first Milwaukee router missing the case and one collet for a song. Another time I picked up a Bosch sander without the case for $24. Clamps and other items used by the ham-handed goofs show up at a fraction of new as well.
A lot of getting a good deal comes from knowing what the regular price is and acting instead of second guessing BUT, don't buy everything just because its cheap; focus, focus, focus. Home Depot has supplied me and Christmas gifts for parties with their $20 shop-vacs that show up on or around Black Friday. There are deals to be had but, I don't think many of them have come AFTER the holidays for me.
P.s. Grizzly's current Christmas flier ain't bad.