Liberty Fund was endowed by the Goodrich family (not the tire people, but the other ones) and has done an amazing job of publishing classics of economics, history, philosophy and biography. Another great book resource is http://isi.org. There are no better places to build your library!
Yes, they have some good books, and the prices are basically subsidized. You would pay three or four times as much for the same book from a scholarly press.
Thanks for the links!