How low-sodium are you aiming for? I track sodium on My Fitness Pal and usually stay around 1500-2000. I believe the USDA recommends 1500 for older folks and folks at risk for heart issues, 2500 for the rest of us.
My answer to your question is exactly what you expect (and probably don't want to hear!): I prepare my own food. For me it's not a task or chore to stop by the farmer's market twice a week. It is not a chore to make my own soups, salads, and casseroles. It's enjoyable. I love learning new recipes and making them while listening to podcasts or NPR or music. It's therapeutic. It allows me to connect with my food- cheesy, I know, but I think the huge distance between us in this day and age and our nourishment is the reason we default to packaged, processed, less nutrient-rich material with which to fuel ourselves. (It also has me standing up and moving around in the kitchen for an hour, which is better than slouching in front of the TV or computer!)
Preparing your own food doesn't have to take long. I have a bit more time now because I work from home, but even when I was working long hours in the office I would usually reserve Sunday as cooking day. I'd cook bran muffins to last me for breakfast through the week, clean vegetables and chop them to be ready to make into salads for lunch, and cook up a casserole, soup, and stir fry to alternate throughout the week for dinner.
I think the transition over to cooking one's own food takes time and can be a little daunting. But once you settle into a pattern, learn some quick recipes (chicken, soup, fish, curries, and stir fries take less than 30 minutes to prepare), where to get your favorite fresh fruits and veggies, it's easy, and you probably won't want to go back to packaged, frozen foods much
Good luck!