I love doing this. My favoured coin/stamp shop has a bin of 35% BELOW face value stamps (usually, the endemic un-postmarked "Permanent" stamps that Canada Post loves to let through, but also torn/folded stamps), and a huge selection of stamps AT face value, many of which are pretty old!! I recently got seven 1934 2-cent stamps for 2 cents each (looked it up: they are "low grade"), and some King George VI penny stamps for 1 cent each... their only problem is that the holes that hold them together are kind of folded (not sure how to use stamp talk for this).