Federal, State, and US Duck Stamp Value

A brand new duck stamp in mint condition was sold in post offices in 1934. Today, such a duck stamp is worth at least $200 in poor condition, and over $700 in mint condition. Not a bad investment!
Today (2007), a mint condition duck stamp costs $15 straight from USPS. A commemorative card costs around $50 and a cachet around $25. Who knows, they'll probably be worth thousands of dollars in $50 years!