Not a bad idea, but also not something new. I know lots of independant greehouses that sell "edible containers", and "patio gardens".

It sounds like a paint-your-own pottery place, but for edible containers! The customisable aspect is what sets you apart from the pre-planted pots in garden centers. Veg gardening design/advice and raised bed/sq foot installs are good value added. This is all strictly novelty though, in my opinion: For the cost of a container (pot, dirt, plants) is the home owner really saving money versus buying the harvested food from a store or farm stand?

I think it really depends on your area/market.

People want their money to go far nowadays, so if they're paying for something fun/neat and get a return on their investment (food!) then you've got a good shot. However, any sort of 'storefront' is gonna cost you, plus your materials (plants, pots). Most businesses have a ramp-up time as word gets around, so we might even be OUT of this by the time you get going. Unless you're willing to advertise the heck out of your business (also affecting your bottom line).

There are lots of container specific vegetable varieties now that may help you, though i imagine you'd have to start them yourself. Tumbling Tom Tomato, Snowy Eggplant, Explosive Ember Pepper ...