An FFL is a special FEDERAL license to engage in the business of buying and selling firearms. Period. It does not guarantee that you can get wholesale prices, that you can set up a store, or that anyone will buy what you are selling. FWIW, most wholesalers deal with established dealers; it is not in their interest to work with "one gun, once a year" dealers.
Further, the state or local authorities may also have rules, regulations or licenses that will be needed before you can engage in the gun business, or any business. That might include, but not be limited to, having a store premises, properly zoned, in which the business will be located, proper security measures (e.g., bars on the windows, alarm system), etc. You also need to have business insurance to protect you and your customer if your store is robbed or there is a fire.
In other words, an FFL is not just a paper to let you buy guns cheap; it is a license to do business. If you want to get into the gun business and make some money (and meet some nice folks, I hope), good luck. But if you only want to buy a few guns cheap, believe me, it will be a lot easier to buy from an established dealer and pay for his (hopefully) better service.
An other angle, seldom addressed in discussing doing business, is that all your good ol' buddies will want you to order guns for them at below dealer prices. A few moments thought will reveal that you can't buy a gun for $400 and sell it for $300 and make money, yet that is just what your "buds" will want you to do. Along with spending all your time in BS sessions with "buds" while cash paying customers get tired and walk out.
Jim