There are people that will pay a few bucks over value, but the $20 bill was used in that style for longer than other bills, so has a lot less value, unless is a special run. With Morgenthau's signature this was printed during WW2(1940's) so its an older bill. You don't see these anymore, Fed has "reclaimed" them to destroy them. Same as Silver Certificates! Keep them!
"Don't believe everything you read on the internet just because there is a picture with a quote next to it" Abraham Lincoln