Start by writing down exactly how you would finance the sstart upof the business, how you would operate it, where you would locate it, who your customers will be, how will you buy and markup merchandise, what are the demographics of your customer area, what is your competition, what is your experience and any other items you can think of. Then does it still look feasible to you? If so then take your plan to the Small Business Administration and have a talk with them. If still convinced, go talk to your bank for financing.
Most small businesses fail bacause the owner did no have ample resources to run the business for 2 or more years until profitable.