$10 Dollar Bill With No Serial Number

I came across this site and saw that you all seem to know allot about collecting. My grandmother used to work for a Bank for pretty much her entire career until she retired and has several rare bills and coins.

I have a question about one specific bill she has and figured this would be a good place to ask. She has a crisp ten dollar bill from the 80's that has no serial number on it. All other seals and markings are on it and the imprint from the serial is stamped on the bill however the ink is missing. She said it came to the bank in a stack of new bills and she kept the bill all these years.

She recently has decided it may be worth something and was interested in selling it. I immediately thought ebay, however that may not be the best way to sell it. My first problem is, we don't know what the bill is worth. I have never seen a shop anywhere in my area that deals in rare coins/bills so I wouldn't even know who to ask what its worth. I don't have a scanner and I really doubt I will be able scan it at a copy place. What would be the best way to find what its worth, and where should I think about selling it?

***Edited by Forum Dad to fix topic title***