Of course. They are in business to make a profit, after all. But from my experience, pawn shops and the like will offer 1/3 to 1/2 (if that much) of the actual value of the item.
The actual value of stamps is how much postal service they can buy. Collectibles have value as long as there is one more collector willing to pay for them. Free appraisals are worth what you pay for them. If one doesn't have the ability and desire to market the collectibles and find the fish buyers, leave money on the table for someone who does. There is only a retail reward for a retail salesman.