Scarcity

State Duck Stamps can be considered scarce for three reasons. First
of all, State Duck Stamps, on the average, have a total sales of about
50,000 copies per year. Federal Duck Stamps and U.S. postage stamps, on
the other hand, have a total annual sales of 2 million copies and 100 million
copies respectively! Secondly, as most Duck Stamps are signed by hunters in
order to validate their licenses, the number of stamps that remain in mint
condition (the greatest value to collectors) is significantly lower.
Finally, states shred any unsold remainders within 3 years.