I agree with Mark. Stamps have taken a real hit as a collectable. I attend a coin show twice a year in Dearborn, and one dealer offers old unused stamps at face value and still seems to bring the same stamps to every show after five years. I have found that most FDCs bring at most a dollar or so apiece. Stamp collectors just don't buy them - but if you have interesting subjects, collectors of that subject might show an interest (Disney, space, etc.).