In Ohio I don't believe any are very expensive, I do know most area sellers don't carry the state stamps and I usually have to go to eBay
. There are also the Junior Duck stamps for collectors also. The Federal and Junior are available through the USPS web site for recent stamps. I am currently 10 stamps away (all newer) from completing my Federal duck stamps, one thing I like I have stamps from my father and I when I went hunting with him many years ago, he has long passed but it brings back great memories.