We spend about $45 a week on two adults---but he has the palate of a five-year-old and would happily eat peanut butter sandwiches for every meal

On a typical shopping trip, we buy bread for lunches, grapes (his only lunch fruit) and a few other on-sale fruits for me, sandwich fixings as needed, soy milk, tomato sauce, canned beans or other dinner items and that's it. We go to a bulk food store once a month and buy rice, pasta, crackers, raisins, oats, nuts and seeds and so on. That's usually about $50 but it lasts a whole month. We also each have one big-ticket item once a month, his is fancy peanut butter at the health food store, mine is pumpernickel bagels from the local bakery. That's $10 a month each and can be covered within the $45 a week limit.
Our typical meals:
Breakfast (me) is a bagel with something on it, or oatmeal with something mixed in (applesauce, raisins, seeds etc.) or sometimes a smoothie. I have no idea what he eats for breakfast. He usually eats at work and says that people always are bringing treats in and he just gets whatever is there.
Lunch (me) is either jarred soup or a sandwich, a veggie (usually baby carrots or snap peas) and grapes or berries. I pack an apple or banana and sometimes some crackers for snack in the afternoon. For him, it's a peanut butter sandwich, grapes and a cookie or treat.
Dinner is usually a fend-for-yourself (in which case, he eats soy cheese sandwiches) or something we eat together. This is often a pita pizza, bowl of pasta (mine with veggies, his without), rice bowl or something simple. I am trying to broaden his palate some, but it's slow going and neither of us particularly enjoy cooking...