Since I have a few Merc dime's of my own, I have to think there's quit a few out there. but still i'm cerious as to which merc's are the most wanted by collectors
I can tell you the ones I need. I have 5 sets started. 1916D (someday maybe), 1921D, 1926S, 1931D. The 1921P is not too hard to find if you can live with a G-4 grade. I paid $35.00 for mine. Also the 1918P is a rather shabby piece in my collections and needs to be upgraded. There are many others I am looking for to fill in the sets. If you want the 1942/1 overdate that is expensive. But to answer your question, the 1916D is the one single date that probably most collectors will never get.