Time to join a food co-op?
Co-ops are owned and operated by their members who pay an initiation fee and agree to work at the store a few hours a week. In exchange, they're able to buy groceries -- often all-natural or organic ones -- at a substantial discount to what they'd pay in a conventional supermarket, with mark-ups over wholesale around 50% less than other stores. If you're interested, us this directory to find a coop in your area.
Before you take the plunge, remember to take into account the value of your time. Working at a grocery store for a few hours a month, attending meetings and having to do your shopping at one location to reap the benefits may not worth it -- you might better off sucking it up, paying retail, and working more at your higher-paying job.