I got the book on ebay and figured that it couldn't hurt. Temple Med's bookstore is on the first floor of the Student Faculty Center (SFC) which is on the corner of Broad and Ontario (about 2 blocks down from the med school). When you do your comparisons, let me know which bookstore has the best prices!
The cheapest web site I've found for medical books is http://www.medsite.com . Usually their price matches my book store so I just purchase from there or if I'm lucky from an upperclassman, but sometimes medsite mails coupons. One time I think that I got a coupon for $50 off a purchase of $150 from there.
There is also the Jefferson bookstore on 11th between Locust and Walnut. I know that we (Jeff students get 10% off cover price, but I'm not sure whether or not it is limited to us, or whether they check at all.