What is a 1875 $20 First National Bank of Grafton Worth?

There are plenty of notes known from the First National Bank of Grafton so a generic note on this bank will not be a great rarity.
There are a handful of examples of the series 1875 $20 dollar bills from the First National Bank of Grafton known to exist.
Even notes from common banks can be worth a decent amount if they are in great condition or they are serial number 1 notes.
If you have any doubts please contact me with a picture of the note. I love to see new national currency.