I've been on a similar budget food wise recently and have managed to eat for around 60-75 a week. Theres a little looseness to my diet right now, trying to gain some clean(ish) weight and have managed to put on 5 pounds in the last 6 weeks while getting my abs to come out more (sporting that 4 pack, now flirting with the bottom 2 coming through). Here's my rough meal outline:
Meal 1: Breakfast egg sandwiches
2 eggs, 3 egg whites, 4 slices of wheat bread, 1/2 banana (save other half for later)
Meal 2: Mid morning smoothie
1 cup frozen fruit, around 1 cup greek yogurt, handful almonds, milk (or water sometimes)
Meal 3: Lunch
Chicken breast (sometimes grilled sometimes in the slow cooker, love the slow cooker), spinach kale baby chard salad mix (comes in a bag at Walmart called power greens for like 2.75 for a bag big, usually go through 2 a week), and then sometimes a half an avocado
Meal 4: smoothie about 45 minutes before workout
1 scoop protein, 1/2 banana, 1/8-1/4 cup oats, water
Meal 5: immediate post workout
jelly sandwich-2 slices white bread and strawberry jam, 1 scoop protein with water
Meal 6: main post workout meal (30-45 minutes after meal 5)
potatoes, any veggies you want (celery and carrots taste really good in the slow cooker when cooked with meat and broth/stock), and then for meat I try and change this meal up week to week to keep a little variety for my taste buds. Sometimes I will go with lean ground turkey, but I really love throwing a pork shoulder in the slow cooker with some apple juice and all the potatoes and veggies, of course the pork shoulder is a good bit fattier than the lean ground turkey option.
Meal 7: pre bed
cottage cheese mixed with a little peanut butter, protein, and milk
I also will have a glass of milk here and there throughout the day with some meals
Main grocery list:
Meat of choice
Initial costs will be higher than 75, but that is just because things like almonds, peanut butter, frozen fruit, oats, and protein powder will last you longer than one week so you won't have to buy these things as often.
Last thing, go shopping the day of or the day before you plan on cooking and find meats that are close to the sell by date and they usually will have a nice discount price on them.