First, do some research and find out which varieties grow well in your area as ALL tomatoes do NOT grow well in ALL locations. IMO, really healthy beautiful plants sell much better than just typical plants sold at grocery and hardware stores. Most, if not all locations that sell plants, get their plants from large growers and the prices they pay will be lower than what you can grow them and make a small profit. So, where to sell your plants? You sell them either on consignment or retail at any location that does not already sell plants. I doubt if any store will take your plants if they already get their plants from a commercial grower as the commercial grower might stop selling to them if they do. The only way, IMO, to sell your plants at these locations is to sell something that is not available by the commercial grower. And since commercial growers grow just about everything you need something different, such as instead of a six-pack of small plants, sell much larger plants in larger containers for a larger price. But this means you must have a green house and start the plants much earlier.
I don't think people really care if a plant is grown from an organic seed. What is important, IMO, is that the plants be marketed as organically grown.