I have a dealer license here in CT, and I can tell you from what my father has told me is that it is not easy to get, and it takes a decent capital investment. Most states require you to have a place of business (not your home), be able to service X number of cars at once, mechanic available (may not be on your payroll), etc.

Right from the horse's mouth:

http://www.dmv.ca.gov/vehindustry/ol/dealer.htm

Regards,
Alan