What is the value of a US 2 dollar bill with Francine Neff's signature?

Francine Neff served as US Treasurer from 1974 to 1977, so her signature was on the 1976 series of $2 bills. That series was the single largest printing of the denomination so if you got the bill in change it's only worth $2. A nice uncirculated one might sell for $3 or $4.