There is also a great place in Rochester, MN that carries a lot of lines that the old Ultimate Electronics used to carry called Midwest Custom Concepts. They are located at 27 9th Street SE (next to K-Mart). They have been doing car and truck accessories for several years now and now that they moved to their new location they are carrying several lines of audio. Alpine, Rockford Fosgate, Boston Acoustics, JVC and Kenwood. Their prices are the lowest I have found anywhere and they also do custom work as well as sub boxes.
I had my truck done there and had a custom fiberglass sub box made. They did EXCELLENT work and treated me right! I couldn't find cheaper prices anywhere. Their show room is huge and I was able to find everything I needed for my truck at one place. They beat Truckin' America's prices for accessories too. Check them out!