Nells250, Very nice piece!
This stamp was on a 5 pound of tobacco package. From the Lee W. Brandom catalog, your stamp seems to be #M-200 or #M-201, depending if it is watermarked on thick paper in the first case or unwatermarked on thin paper in the second case. As for value, the given prices (from 1976) are 1.00$ and 1.50$.
The given price is said to be a "rarity factor" only. I heard that we could multiply this price by 10 to get an approximation of today value, but it does not seems to be enough with what I can see on the Internet. It is still a mystery how to correctly value those "tax paid" tobacco stamps. I once send an e-mail to a guy at BNAPS (
http://www.bnaps.org/; Lee Brandom was/is (??) a member of BNAPS) asking if there were any price update and nobody ever took over M. Brandom's work. So, I do not know how dealers calculate their sales prices. If anyone have any idea, feel free to explain!