It would be nice to have a half acre of decent dirt to raise some food on but living in the city I have far less than that. We do have a few nice beds and a fantastic plum tree in the yard we share with our building. So, instead of trying to square foot garden enough tomatoes for a season or a bed of potatoes I've focused my efforts on a great herb garden. I also grow a few things that are really more than herbs but serve to flavor other things rather than being a dish unto themselves. Garlic and shallots are really simple and go with about anything. They can both be grown in the ground or in pots and can even be used as edible centerpieces or decorative plants. You haven't tasted garlic until you've had green garlic. Just plant the cloves and use the greens like you would green onions. Truly fantastic.
In essence you can buy a lot of potatoes for next to nothing and then throw in some fresh herbs and make something really great, often something that simply can't be had in most stores.
Today's farmers market was a little on the ordinary side but I still managed to find an heirloom variety of mustard, some miner's lettuce and another type or rosemary for the garden. They'll go nicely with many of the things already out there ranging from Roman myrtle to several varieties of lavender and mint. I even have a patch of dandelions coming along nicely for the greens and maybe an attempt at dandelion jelly.
Even if only a simple window box is all you can manage give growing something a try!