Farmers markets need research too
It's easy to assume that, since you're buying from a farmer, that his products are automatically better than anything you can buy at a store. We won't debate that, per se, but look at what's around me:
SMM Our Farms
A majority of them may pasture their pigs / cows for a while, but much like conventional animals they are finished on grain. Conditions are likely better, but I have not been able to witness this first hand.
Visited a big FM last weekend. One of them had chickens and eggs cheaper than others. Turns out he fed them soy and something else grown on a neighboring farm, so not organic. They were free range and had no chemicals, but not organic.
Your best bet is to look for the farmer's market web site and put in requests to the market manager. They are the ones who find producers.
We are in the process of trying to create a local, organic/sustainable market for our neighborhood. We are interviewing providers and looking at what we need in terms of grant funding to get off the ground. Because we are starting it, we can really pick the producers ourselves.
There are other local markets that are like farmer's markets, but they are basicaly distributors, not direct from farms. And, most everything is conventionally grown.
So far, there is only one local/organic/sustainable market in our city, and I think there is definitely room for more.