Raised bed, $300, dirt to fill (after adding a bottom layer of goat compost and miscellaneous paper/brown scraps), $150, seeds, $20 (granted you don't use all the seeds in each envelope, so if you freeze them they may sprout next year). Expected yield per year? $150 if you don't suck as a gardener? Maybe? Or, you could put that money in the bank and buy groceries as you need them.