Brands aside
Another thing to remeber is this business will be YOUR business. Don't think it's 40 hour per week. Well, you can think that way if you don't really want to succeed.
Plenty of pictures, representations, and testimonials will do wonders. And also, the mark-up on your products is not where you will define yourself, or make your money. It will be (from what I've read and what I've encountered) the custom, quality installs.
FYI- JL Audio doesn't allow internet sales, and Focal wants to see a plethora of SQ trophies before they trust you with their license / warranty (no internet sales either). Eclipse is about the same thing, but I hear they will be sold in Best Buy before 2006.
I wish you the best.
Karl Burns