I have found Roll Models to have the least expensive prices by far! Takes them longer to ship though compared to Squadron. However, their shipping times (2 - 3 weeks) are comparable to just about any other online hobby supply I've done business with.
Dad always said, "There's a difference between Miss Right and Miss Right Now." If you are looking for the Miss Right item, go online. If you are looking for a Miss Right Now item, go to your local hobby store.
http://www.rollmodels.com/
These are also two more sites great for finding online and local resources.
http://www.hobbyretailer.com/
http://www.scalemodelindex.com/
The links at these sites are pretty accurate, but the business listed might not be around anymore; such is the case with my local hobby shop. NOOOOO!!!