Tough to tell from pics. Try to see it in hand. Check for security fibers, feel, and smell(make sure has no chemical smell whatsoever). If everything checks out, make him an offer. He's either been lowballed by a dealer and wants to try and get more online or dealer found it to be man made error and didn't want to buy.
He is looking for $275. I am not sure I even want to get involved. I have a bad habit of buying everything I can. I might just let this one die. I think I would have a dealer look at it before I bought.
I would stay away from it for $275, highest I'd personally go if it were authentic would be around $100. Errors are a tough market, not alot of error collectors out there, and they aren't looking to pay what book value lists them to be worth. An error like this isn't that rare, only the rarest seem to hold there value.
That would be nice to find. I don't find much searching bills, some radars and stuff. I got a $20 birthday bill of which the birthday woudl be 1930. I do not know if anyone want sthat though or if they look for more modern birthdays.