Cathy, you're right. I am passionate about heirlooms. In fact, I will not put a hybrid in the ground---as much for political reasons as horticultural ones.
As to availability, heirloom seeds are everywhere, nowadays. Even the mainstream seed houses, like Burpee, offer some. And there are at least two dozen companies that specialize in heirlooms. Among them:
Southern Exposure Seed Exchange
Baker Creek Heirloom Seeds
Tomato Grower's Supply
Victory Seeds
You can find them, and many others, on-line.
There also are several seed-saving organizations you should check out.
Seed Savers Exchange (SSE) is the largest such group in the world. In addition to their growers exchange proceedure they have a public catalog, where anyone can order seeds. Find them at
Seed Savers Exchange.
Appalachian Heirloom Seed Conservancy, of which I'm the managing director. Specializes in preserving the edible foods of the mountain south. No web page, but you can reach AHSC at
KentuckySeeds@hotmail.com for membership info. Be sure an include your snail-mail addy.
Southern Legacy Seed Project & PASS (Pass Along Southern Seeds) based at the University of Georgia.
And there are a few really specialized ones, such as Native Seeds/SEARCH, which specializing in collecting native crops of the Southwest and northern Mexico, and re-establishing them among native peoples.
There are, too, individual growers who offer seeds at seed swaps, and spring gardening meets, and on line. For instance, I'll have a large display on hand when I give my seed-starting presentation at a local library next month.
The benefits of heirlooms are legion.
First and foremost is flavor. Families have passed these down, one generation to the next, because they taste good. Flavor has been the sole selection criterium. The same cannot be said about hybrids.
Hybrids are selected to meet the needs of the food distribution system. Flavor is not one of those needs, and when a hybrid has good flavor it's because it sneaks in by accident as part of the overall genetic mix.
Second is seed saving. You can save seed from open pollinated plants, and, in the absence of mutations or cross pollination, they will breed true to type. With hybrids, on the other hand, as the old commercial says, you don't know what you're getting. They do not breed true to type.
Next is bio-diversity. Virtually every major agricultural disaster of the past several hundred years resulted from there being a limited number, of genetically similar varities. A new blight appears, and wipes out the crop.
Do you want to put all your marbles in the half dozen hybrid tomatoes that Monsanto et als offers you? Or would you rather make your choice from the 6,000 or so known open pollinated varieties.
The only exception to all this are beans. Despite what the seed houses would like you to believe (so they can keep selling you seed) there are no hybrid beans. They are all---all 10,000 or so of them---open pollinated.
Whew! I reckon that's a little more than you wanted to know.