If they're going to eat grains and legumes and stuff you should learn to prepare it in a traditional way, such as making sourdough bread.
IMO the best grains and legumes dishes are either dosas or idli (fermented mixture of mung or adzuki beans with brown or red cargo rice) or rice and optional beans first fermented a bit with whey and then cooked slowly with meat broth.
Nourishing traditions and Cure tooth decay have very good advice for making the SAD diet better. Weston Price said that one good meal a day improved tooth health I think 95%, even when the rest of the day's meals contained white flour and white sugar products.
Really the best bet for cheap food IMO is potatoes. Wouldn't be hard at all to grow your own in your own back yard either.
Oh and it's very possible to get a dairy farmer to give you large quantities of raw milk for rather cheap. Gotta find a good pasture based one though or it probably ain't worth it.
You could always get your own dairy cow!
I won't argue whether raw meat or raw milk is a better product, I really don't know personally. The reason why I chose to consume more milk than meat is because of the ease, because I like it better (though not all of the time, variety rules) and because milk is far superior in the economic department. I could keep one beef cow and raise her offspring for meat and get less than 600 pounds of meat a year or I could keep a dairy cow and get 10k pounds of milk a year + less than 400 pounds of meat a year, but just as much bones and guts as a beef cow.
Oh this thread is about coconuts! Sorry to take it so far off topic!