You wanna buy EMPTY bottles?!?!
If I purchase any bottles, they come with great beer in them. Any microbrew you can find, with few exceptions will be in capaable bottles, all you need to do is soak them in oxyclean and the labels will slip off.
Even some macro beers come in crown rather than twist off bottles. One of my favorite is Bud American Ale bottles, they have a unique shape, the beer is not as nasty as their other products and it's cheaper than most micros.
But there are plenty of options for homebrewers that don't cost anything.
It seems at first that accumulating bottles is difficult but if you mention around to people that you brew and need crown bottles they will start showing up. There's also craigslist, and freecycle.org, hooking up with other homebrewers, recycling centers. Asking at beerstores that have a good selection of beer for their returnables. Some stores will let you have their empties for the price of the deposit. And some bars will give you all you can haul out if you ask.
Also if you want to bottle in champagne bottles, go to a hall that does weddings, heck even a moose or vfw hall, you might just have to dumpster dive at worst, or just pick cases of empty asti bottles by the back door.
It seems daunting but you'll get plenty really fast.