I think a big concern is the bears, because they can get through anything if they're determined. We don't often have problems with them in Florida, but a friend with a house near a lake had a tenants coop smashed up by a bear at night. We have a member who deals with bears regularly in Colorado and baits electric wire to teach them to stay away.
On feed, you'll get the best bang for your buck avoiding less nutritious items like corn and scratch and stick with nutritionally balanced feed. A layer pellet with a minimum of 16% protein, although many of us choose a higher protein 20% all-flock or grower with oyster shell on the side. Corn just doesn't do much, so it's kind of a waste of funds, and you want to avoid too much fat because that can lead to laying issues that won't get you a return on investment. Some people are focusing on the short term and what's the cheapest, but your goal seems to be to create something sustainable and for that you need healthy birds.
I don't know if you're putting in a garden but I have some seeds for tomatoes and other stuff if you want to pm me your addy or po box?
Anyway, one thing you might consider is some breeds are much more economical to feed than others. Leghorns, for example, were bred by big agriculture to do the most with the least. Wyandottes are among the worst, from what I remember according to a chart that was floating around here. That's not just about eggs but also pounds of meat for pounds of feed.
When it comes to sourcing local birds, just keep in mind they won't be as productive after a certain age. Those of us with showy breeds don't often mind getting half as many eggs after a few years (depending on the breed), but the most economical system would be hens under 2-3 years old.
One kinda redneck idea, which I'm only mentioning because your neighbors might not mind, is to convert a derelict vehicle into a coop. The side windows get the mesh, windshield stays, and seats come out. It's kinda crazy but a car is a tough thing, lol.