That's the thing. Gardening is more expensive than buying food, in the United States and Western Europe, now, because the real cost of food production is heavily subsidized by our governments and we guarantee yields by throwing tons of fossil fuels and their derivatives at the soil of corporate megafarms. There's a nonzero chance that's going to change shortly - probably within a generation - for a ton of reasons including but not limited to little Donnie assassinating the supreme leader of Iran for shits and giggles.

Grow a garden even if it's not economically efficient. Do it now, when you aren't relying on it for food, and get the issues with soil and drainage and so on worked out now. Learn to save seeds and select the best growing plants each year so that, as your climate changes, the varieties you grow change with it. That way you'll have the skills to do it later, when you really need it.