It retails at $59.95 from the NIC (NorthAmerican Interfraternity Conference).
Baird’s Manual of American College Fraternities (20th Edition). The 20th edition is the 1991 edition incidentally.
Link to relevant NIC page.
edited to add: earlier in this thread this link was posted:
http://www.greekpages.com/resources/bairds.html
The page described the book and told where you could get it - from the "Bairds Manual Foundation" and gives their address. That address is the address of the NIC.