My favorite numismatic book of all time was written by Cornelius Vermeule and is Numismatic Art in America-Aesthetics of the United States Coinage. It is long out of print, but Whitman published a new edition a year or two ago. I have not looked at the new edition. Recently, I finished Roger Burdette's outstanding trio of numismatic books and am now reading The Art and Craft of Coinmaking-A History of Minting Technology by Denis Cooper.
Yes! A phenomenal book. I've heard him lecture, he's extremely passionate. The most important contribution to the study of the Roman economy is really the explanation of the tax system and the importance of coinage to it. If you're interested in this, I recommend you read some other books too: Andreau, Jean 1999 Banking and Business in the Roman World. Cambridge University Press, Cambridge. Bang, Peter Fibiger 2008 The Roman Bazaar: A Comparative Study of Trade and Markets in a Tributary Empire. Cambridge University Press, Cambridge. Finley, Moses I. 1985 [1970] The Ancient Economy. University of California Press, Berkeley and Los Angeles. Rostovtsev, Michael 1926 The Social & Economic History of the Roman Empire. Clarendon Press, Oxford. Another outstanding work. I'm not reading any books at the moment, per se, but I am working through the articles in the 2009 issue of The American Journal of Numismatics. Outstanding scholarship in there.