I have ordered through this online wholesaler about 6 times now, about $1,000 in parts total with no problems.
http://www.the-best-source.com
Otherwise, I like the dealership. They are expensive on some items, other items are quite reasonable. Napa Auto is OK for quick parts. I do not recommend Pep Boys, Checker Auto, Autozone, B2B, O'Reilly's, Walmart, etc. The local salvage yard is a great place as well depending on the part necessary. Be prepared to bargain. Parts are cheap compared to labor, so buy quality parts.