I know you can buy beer right from a bar, or from a distributor. It used to be that you had to buy it by the case. Maybe that's changed. When I visit my brother I usually bring it in from NY, or pick it up in Ohio. I know there are very specific hours and days you can and can't buy beer.
Here's Wikipedia:
Beer may only be purchased from a restaurant, bar, licensed beer store, or distributor. Beer distributors mainly sell cases and kegs of beer, not smaller volumes of beer such as six packs. Six and twelve packs, along with individual bottles such as 40 ounce or 24 ounce beers, are sold at bars, restaurants, and licensed retailers. A licensee can sell up to 192 fluid ounces of beer per purchase. For larger quantities one must go to a beverage distributor which sells beer only by the case or keg. Beverage distributors (which also sell soft drinks) may sell beer and malt liquor, but not wine or hard liquor. Unlike the Wine and Spirits shops, people under 21 may enter most beverage distributors without an adult, since most distributors also sell water, soda, ice, and some snack foods. They are subject to the rules of the individual establishment.