you could always get a vendor license and set up shop on the side of the road, if your town allows that. if not, post up signs a week in advance and have a "yard sale". keep your prices low because you have to remember that a lot of these same plants can be purchased from a nursery or home depot fairly cheap too and they are grown by professionals but they also dont get the same love and attention that a private grower gives.
my roommate did it like this... post up signs around town for a yard sale with organic veggie/herb plants and people came from all over town to get them. as long as the plants dont have veggies on them you should be clear of any legal issues (selling food with no permits etc)
his prices were based on large and small. the small plants were in party cups and were $5 each. Small tomato plants, purple basil, oregano, dill, chamomile, some cukes... all $5. the large plants were tomatoes, squash, bell pepper, zucchini, and some tuber plant that is related to sun flowers and kinda looks like sun flowers.. forget what they are called.. the large plants for $11.
i love supporting people that grow their own crop and sell it (at a reasonable price).. just make sure the plants you sell are healthier than what you get at the local nurseries.