What you will need;
1- DEEP POCKETS !! In operating capitol you'll need 5 figures. This will be for marketing, equipment, insurance, and to off-set the dreaded charge backs.
2- A retail store front. DTV is looking for dealers with store fronts and at least 2 years in some sort of retail business.
3- Being OK with no life. Once you become a retailer you will now have no life. It is a 7 days a week, 12-16 hr a day job.
Most installers think they can be retailers when the facts are that 9 out of 10 fail within the first 6 months with any money they had saved up gone.
You will be much better off running sales through someone and doing the installs. You will have no money out of pocket and your charge backs will be lighter.