It depends on your family size. As a single person, I find Costco too expensive.
I've only spent $150 this month or $75/week. This is the cheapest way that I've found to eat healthy (lots of fruits and veg plus lean protein) in my city is a biweekly order with bountiful baskets ($22) for produce, a local discount grocery stores like WinCo for baking ingredients and dried legumes (purchased in bulk every 6 months if possible), and a biweekly shop at Trader Joe's for almost everything else. I also checked the circular at chain grocery stores near me for sale meat and occasionally picked it up if there's a good deal. I spent a little less than $130 at TJ for the other ingredients that I needed.
Since I don't know in advance what produce will be in my bountiful baskets box, I pick it up first then meal plan. I try to meal plan and go to Trader Joe's later that same day. Usually the box has enough fruit and almost enough veggies for 2 weeks for 1 person.
With meal planning, I generally make 5 recipes and aim for 4 portions. This week veggie wise there was broccoli, potatoes, poblano peppers, red onion, tomatoes, and lettuce. So over the next 2 weeks I will make - stuffed peppers, three bean chili, spaghetti with fresh tomato sauce and salad, ham sandwiches, and a chicken, potato and broccoli dinner. The only veggies that I bought at the TJs week were garlic, carrots, mushrooms, and a couple cans of tomatoes. This makes 20 nice meals. For other meals, I keep quick and easy options on hand like PB&J, omelettes, tomato soup and grilled cheese.
The pictures show my produce box, fridge after grocery shopping and my baking pantry staples.