I don't think gold certificates were ever actually demonetized; you just had to trade them in for other currency. They're still worth face value if you've got one. (Unless it's one of those cancelled 1900 $10000's, but the key word there is "cancelled".) I've heard conflicting stories on the Fractionals: either they're still legal tender but not redeemable, or they're still redeemable but not legal tender. Part of the problem is that I'm not sure whether what happened in 1962 was a Congressional action or just a change in Treasury policy; if the latter, then I don't think the Treasury has the power to demonetize anything....
About 20% of the note is missing, so I would only pay $16. for it..Just kidding. Frankly I wouldn't pay anything. It's the worst looking note I have ever seen.
In an article that I read the Treasury will not redeem any fractional currency from 1962 forward, as to being legal tender or not I am not so sure. I do not think that an Act of Congress was passed, just that the Treasury stopped it's redemption...but I am not 100% certain on this matter. I have heard that there are ~2MM in unredeemed fractionals left over from the 368.7 MM $$ printed. Regards, RickieB