Hmmm... so you want to open a sneaker store (consignment).
Few things to think about.
1) How much expendable income do you have? Meaning, how much money can you dump into this project right now and still be able to feed yourself, clothe yourself, and shelter yourself? To open a sneaker/clothing store (non-consignment) after all the start up fees, random costs that are relevant to licenses, renovations, etc. and placing initial orders (if you're credit is good enough, most major brands aren't going to let you COD) you're look at minimum $75,000, optimum $175,000.
2) Do you have connects? REAL connects. Like, a manager at your local footaction who'll let you get as many Cool Grey's as you want when they release for at least 30% off retail so that you can sell them at retail or slightly higher and not be caught in the wave of everyone selling them at "aftermarket" value. Because if you're buying at retail ($175) and selling for anything less than say, $250, you're wasting time and money because the cost of overhead will outweigh the $50 or so dollars profit you see.
3) Do you have backstock already available? Have you been putting FSR's to the side of popular shoes that have high re-sale value for a while now? Because if you can easily access it now, chances are no one wanted it when it first released.
There are other things to think about... but to be honest kid, unless you've got something that's going to REALLY make your store stand out from the major players in consignment, it's a TERRIBLE idea. There's Flight Club and then there's everyone else.
Don't do it.