lol, yah, the above post pretty much tells you how to do basically..
first of all, you'd probably need to contact whichever breeders gear that you'd like to start to carry, and ask about selling their gear at your store..
the thing is that if you're in the us, even the simple possession of cannabis seeds is illegal, so you can pretty much forget about trying to set up a store in the us to sell them, unless of course you lived in a mmj state, and owned like a dispensary or something along those lines.
even doing this would still be against federal laws, and depending on how big you became, you'd more than likely got busted / forced to shut down, if not both..
idk if you know who marc emery was / is, but he had a seedbank based out of canada, and his big motto was overgrow the gvt, and he was very active in the legalization of mj.. he also liked to call himself the prince of cannabis, and had been interviewd by some very big us publications, all of which brought him to the eyes of the us gvt..
when all was said and done, marc is now residing in a us prison for all sorts of charges stemming from his canadian seedbank..