They absolutely can be!! However, it all depends on year, condition and *rarity*. If it is a $2 note in Choice Uncirculated from, say, 1999, it could already be worth $8-10. If it is a rarer note, such as a *star note, then that figure at least doubles! Look at the note and ask yourself, would I be willing to pay more than $2 for it in this condition? If no, then spend, if yes, then hold.
I think there is a potential there depending on the condition of course. I would say more likely the 1976 issues have a higher value. I would hold on to them.
