I have a 1981 50 star note serial J00777698, in uncirculated condition, but I can’t get a print number or value anywhere
The "Redbook of United States Paper Money" would have that information. I have the 6th edition, but a 7th one just came out. We would need to know the Federal Reserve Bank and whether it's a 1981 or a 1981-A. The most valuable star notes of that year for a $50 are, according to the book: Chicago, New York, Cleveland and a few others. The most valuable seems to be a 1981-A from Richmond. General values for all issues that year range from $80 - $475.
Underneath the serial number should be the Federal Reserve Bank code, something like "A1," "E5," or "J10."
That's a Kansas City 1981 starnote. The Redbook has this to say about it: Quantity Printed: 128,000; Value in Unc-63: $250 Catalog No. F-2120J*
A guide gets you into the ballpark. By checking past auction results, I would value an uncirculated 1981 $50 KC replacement note between $100 and $150, maybe more if graded.
Doesn't look quite unc to me. Seeing a light crimp at the bottom center or it could be the pic. Anyway I'd say never expect book value. That's what a dealer will ask. Plus any denomination above a 20 is harder to sell. Just because face value is already 50 bucks. A nice looking note though.