Depends on what kind of growing your doing. There are a lot of agriculture styles that use very little resources and are economically affordable. If you're doing row-style monoculture, then you really can't compete with those economies of scale (and subsidies). But permaculture has huge yields for the amount of input it requires. Cultivating fruit trees and perennials in a plant "guild" can produce resilient, long term food sources with little upkeep. You could easily grow enough food for yourself on an acre.