It's been a rough couple of years for vegan yogurt. First, Whole Soy & Co shut down production as they built a new facility. Wildwood disappeared from shelves locally, without so much as a goodbye. So Delicious released a coconut yogurt, but it was sweetened. Whole Soy came back, and after a few gritty batches, became a luxury purchase at $1.99 a serving. Also, still no unsweetened plain. I assumed I'd never be able to make my sweet potato chili again. Then, Chelsea over at Suzie V. Homemaker told me how easy it was to make my own.
I ordered a yogurt machine online (the EuroCuisine one was a steal at $14.95), a box of vegan yogurt starter (I ordered this one, and now they've started carrying it at Whole Foods), and headed to Trader Joe's for soy milk. I read that it was best to use soy milk with very little added to it; especially without carageenan, because it may hinder the culture process. Westsoy soy milks are purely soy beans and water, and maybe vanilla. The Trader Joe's brand organic, plain, unsweetened soy milk is the same, and a steal at $1.69 for a quart in an aseptic box. I got one of those, and a quart of Westsoy vanilla.
I did entirely too much work for my first batch; heating the milk, cooling it, whisking in the starter, and finally breaking my candy thermometer. Then Chelsea pointed out that I could skip the heating part, since the milk was in the aseptic container. Also, no cornstarch, agar, pectin, etc was needed to thicken. A good 8-10 hours in the yogurt machine made seven little jars of soygurt, for a fraction of what it would cost to buy it already made. Once the jars are cooled, mix in fruit, maple syrup, lemon juice, or whatever you like in your yogurt. Use plain for recipes, dressings, and vegan cheeses.