Request for information on book purchasing

["Joseph J. Esposito" <espositoj@gmail.com>]

Perhaps members of this list can assist me in answering some 
questions about the purchase of books by academic libraries.

By "books" I mean something specific:  printed books published by 
university presses.  No ebooks, no digital aggregations, nothing 
from publishers outside the university press world.

The question is, How are libraries purchasing these books?  One 
press director told me that all the purchases go through library 
wholesalers (e.g., Baker & Taylow).  I understand that some 
libraries are purchasing such books from Amazon, but I have not 
yet had a librarian confirm this.

Do you have any figures on this?  Of all the U. press books you 
purchase, what percentage comes from wholesalers, what percentage 
directly from the publishers, how many from Amazon or other 
(principally) retail vendors, etc.?  A related question is, Do 
you get significantly different figures if you count by units 
(that is, copies of books) instead of dollars (the cost)?

Thank you for your help with this.

Joe Esposito