I don't think the problem is strictly with osteopathic schools but with medical schools in general (except state-supported). Of course, some schools have more scholarships available to medical students.
For example, in the Philly area
PCOM tuition + fees - $35,298 (2006-2007)
http://www.pcom.edu/Administration/Administrative_Departments/Bursar_s_Office/do_tuition.html
Jefferson tuition - $40,701 (2007-2008)
http://www.jefferson.edu/registrar/tuition.cfm
Penn's tuition + required fees - $41163 (2006-2007)
http://www.med.upenn.edu/admiss/financial.html
Drexel tuition + fees - $39970 (2006-2007)
http://webcampus.drexelmed.edu/admissions/financialaid.asp
Temple tuition + fees - PA resident $36,220, $44,248 for non-state resident (2006-2007)
http://www.temple.edu/bursar/about/tuitionrates.htm
For Chicago
CCOM tuition - IL resident $38,211, non-state resident $42,517 (2007-2008)
http://www.midwestern.edu/content/lc401.asp
University of Chicago - $35,305 (2007-2008, MS1-MS2 years only)
http://pritzker.bsd.uchicago.edu/admissions/financialaid/budget.shtml
University of Illinois Chicago - IL resident $12,354, non-state resident $26,381 (2006-2007)
http://www.uic.edu/depts/oar/rr/tuition_fees_2006_2007.html
Northwestern University - $38,613 (2006-2007)
http://www.northwestern.edu/sfs/feinberg/tuition.html
Loyola University Chicago - $36,600 (2007-2008)
http://www.meddean.luc.edu/admissions/finaid.htm
Rosalind Franklin University Chicago Medical School - $36,740 (2007-2008 estimated)
http://66.99.255.20/osa/financialaid/0400_2008studentBudgets.cfm