How to eat clean on a fixed low budget??

Eggs are probably your best protein source. At a couple of dollars a dozen, there's nothing else that comes close to giving you lots of high-quality protein for relatively little money. Milk i also a good choice.

Potatoes, carrots and dried beans. Check out a good recipe for lentil soup that uses the carrots, potatoes and onion, another relative cheapie. A huge pot costs just a few dollars.

If there are ethnic food markets in your area (Hispanic, Asian etc), I find their prices on produce are like half that of the regular supermarkets. 99-cent store also can be a good source.

At the farners market, the stalls that sell beets and carrots are usually asked by shoppers to remove the greens, and I find they're happy to give those away rather than throw them out. Every time I go down there, I come back with a big bag of healthy greens that cost nothing.

I hope this helps. Not an easy task, trying to do this with two teenage boys. Good for you for giving it your best try, and your boys will benefit, too.

Frozen fruits and vegetables.
Dried beans are one of the best bargains in the store.
Buy meats and fresh fruits/vegetables only when on sale.
Stock up on non-perishables when on sale.
Coupons

If possible, grow some of your own food. Even a small garden can provide a lot of food, and many vegetables can be grown in containers.

ETA: Your post says "The first two weeks I'm good. But the last 2 weeks I'm stuck with making bad choices." What are the bad choices that are cheaper?

Do you have a Walmart and an Aldi(or similar) where you are? Since Walmart matches prices I take the ad from Aldi who always has produce at amazing prices (banana 27cents a pound) and I stock my basket with every fruit and veggie in the add. I shop all other grocery stores for only what is on the front and back of their weekly flier. Those are their best in the store prices. Just suggestions on the fresh stuff.

Eating clean on a low budget can be tough to manage. It's not easy. Is it just you and the growing boys? If so, I'd try to split it in 3rds. Are they picky? do your boys strive to eat healthy too? Are you cooking their meals and are they eating them. Find a common ground to work from. My family wasn't terribly impressed with the healthy way of living in our home when I first started off; but determination and conversing with the family is the best place to start! Feel free to add me?

http://www.forksoverknives.com/my-1-50-a-day-challenge-eating-a-plant-based-diet-on-an-austere-budget/#.UjCLo_FvA5A.twitter

You don't have to be that extreme, but it's possible :-)

If you buy a lot "organic", "natural" labeled things... (or so they are marketed) it's going to cost a lot.

Think in terms of whole, food in their original and unprocessed form. It can actually be cheaper if you plan it out.

Step one: The farmer's market is your friend. For real. Buy in season fruits and vegetables from your local farmers. It is often less expensive than grocery stores... The quality will be practically unbeatable. Plus: they often give deals to regular customers and you're supporting your local markets.

Or better yet!: if you're able considering having your own little garden. Even a small space can pack in a lot of healthy produce.

Step two: Go to the "bulk bins" in the grocery store. I'm not sure if this is the exact term for it... but that's what I call them. They have bag your own oatmeal, beans, rice, granola, grains, and sometimes even candy (hey: you have to have some sweets in there too). These are usually way cheaper than the prepackaged stuff.

Step three: Buy your meat in bulk if you can. Sometimes you can score awesome deals if you buy a quarter of a cow or pig. Bargain shop. Ask around. Also: don't underestimate the power of canned tuna. It is delicious and nutritious. Eggs are also an amazing source of inexpensive protein.

Step four: Buy store brand and don't be fooled by "natural" and low fat foods. These are often geared toward dieters and vendors know that when you're watching your weight you're often more willing to fork over more money. Also look for good deals in your local circular.

Step five: Make a promise to yourself (and make sure your boys know it too!): no more mac and cheese and ramen. None. There are plenty of options out there that are just as cheap and way more healthy.

Good luck.

Make food from scratch. Processed "convenience foods" carry a high price premium.

Example: A good can of chili will run me $2.50-$3.50 per can. I make it from scratch for about $1.25. I eat chili once or twice every week, so I save around $300/yr just for this one item. I did have to buy a pressure cooker and canning supplies so I could only cook chili once every three months (big batches, spices per the chef's taste buds that day .

I buy raw food ingredients in bullk: pinto and kidney beans, wheat kernels, honey......etc.

I'm not real concerned about toxins (e.g. pesticides etc.). A majority of the raw foods have MUCH LESS foreign toxin type stuff in them compared to the processed foods which have at a minimum, lots of preservatives. Thus, without even going to extremes, like buying organic an premium prices, you can reduce your food costs and eat "cleaner" just by making the food yourself from scratch.

Currently, I make the following
Bread, bagels, belgum waffles, cinnamon rolls
Refried beans, baked beans, chili
Chicken soup, French onion soup
Chicken slices for sandwiches
Canned tomatoes (from my garden), canned tomato sauce, canned spaghetti sauce
Canned peas, green beans (and other stuff from the garden).

I don't know if you can save money canning fresh vegetables from the store. I grow over 33 edible things in my yard, so I don't have to investigate cost savings of veggies, fruits, or berries in bulk/then canned or frozen (e.g. raspberries, blackberries) from a store.

Good luck!