Thanks to the blog Love in the Time of Chasmosaurs for the notice about Indiana University Press spring/summer book sale with some books marked down 80% with free U.S. ground shipping for orders of $25 or more. Enter code WWEZXX at checkout to receive discounts, quantities limited and sale ends 06/30/2010.
I like Echinoderm Paleobiology for $36 and Oceans of Kansas for $24. If you like dinosaurs, they have quite a few books on sale.
Books of interest Limestone Lives - Voices from the Indiana Stone Belt by Katherine Ferrucci at $21 and This Place We Call Home - A History of Clark County, Indiana by Carl E. Kramer at $21.