I found a copy of this http://www.amazon.com/In-Season-Cooking-Vegetables-Fruits/dp/0789318113/ref=sr_1_1?s=books&ie=UTF8&qid=1332442038&sr=1-1 on the sidewalk last year when I was first thinking about buying local, seasonal produce.
I eat mainly vegetables and try eat local as much as possible. I'd never really given thought to it, but things are available all year round in the supermarket now. It wasn't like that when I was growing up (or maybe just not where I grew up), and food just doesn't taste the same. Now I try to pay attention to what's in season locally. There's a big difference in taste.
We try to go to the farmers market regularly, even if we don't buy, we walk around to see what's available as it helps us to learn what's in season for mealplanning and supermarket trips. I find the farmers markets pricy. I go to the one in Carroll Gdns and the one on Atlantic Avenue. There are a couple of vegetable only stores around here, but their produce always looks fake. It is cheaper though. Are those what you mean by "wholesale".
Supermarkets are sneaky though. Union Market has "locally grown" signs on some of their produce, like spinach, but if you look it's actually grown in Florida over the winter and more locally in the summer.