how do you START a beehive? where do you get them?
You buy the hive/gear, and then order a package of bees.
There should be at least one, likely more, beekeeper supply stores in your area, where you can pick up the basic hive setup for less than $200. Here in Salt Lake, our local farm supply store, IFA, has started carrying beekeeping supplies as well. You can also hunt around on Craigslist for people selling surplus equipment. If you are at all handy, and are interested in the more natural keeping methods, you can build your own Warre hive or Top Bar Hive. Check out Biobees.com for dowloadable PDFs for both hives, as well as books, podcasts, and a forum where natural keeping enthusiasts from all over share ideas and tips.
There are two ways to get bees, either a swarm or a package. It's possible to catch a swarm, but you can't count on being that lucky. Look for local bee swarm removers, they often sell the swarms they remove for a reasonable price. Or, you can just order a spring package. Most large scale operations sell 3lb packages of bees in the spring, with a mated queen, for about $100. They come in wooden box with screened sides, and you basically just open the box and pour them into the hive. Once in a hive, a swarm or package will likely stay put and immediately start building comb and laying eggs. Sometimes you can get Nucs, which as are small boxes with frames of honey and brood, with worker bees and a laying queen. Nucs are easier to establish, but are more expensive, and only work with the traditional Langstroth hive, not the Warre or Top Bar Hive I recommend.
No matter which hive type or keeping method you choose, you may want to educate yourself first. Look for local beekeeping clubs, they may offer classes or can put you in touch with a mentor. The IFA here not only sells equipment, they sell packages of Italian bees each spring, and offer classes all summer long.
The best time to order a package of bees is early to mid february, any later and they sell out.