If I were homeless, I would not forage or dumpster dive as a first option, because it would be important for me not to accidentally get sick. Instead, I would fully take advantage of local foodbanks. The Greater Boston Food Bank, for example, has fairly nutritious menu options. There is less processed food on their shelves than in an average person's kitchen.

Sometimes, getting calories is more important than getting strict paleo foods, if you are very low on money. More tubers could help, as could cheeses, coconut milks, etc. For protein, stew beef is cheap.

Locally, we have a "hunters against hunger" program that gets hunters to clean out their deep freezes twice a year and donate the meat to food pantries, homeless kitchens, etc. It keeps game meat and fowl available in the various shelters/kitchens here. Now wether or not that food kitchen breads and fries that meat in soy bean oil is another story....

Canned tuna in just water or oil. Pretty inexpensive and 5 oz of meat each can. And it's already cooked!

Two words: chuck roasts.

My local Kroger (big supermarket chain) had them on sale for $3.49/lb. Oh and it was buy one get one, so cut that price in half.

Meanwhile, filet mignon and ribeye prices were ridiculous. These big stores set low advertised prices on certain meat items to get people in the store. Abuse them by walking in and spending the $50 you just got at the plasma center on buy one get one chuck roast and you've just walked away with 20 king-sized meals...that's over 30 pounds of meat). AND you're eligible to donate plasma again, in only two days' time. This leaves you with enough for gas, garlic, Trader Joe's wine, and canned sardines for the lean times ahead.

Dumpster diving is a great option!!

I know people here in SoCal who hold down perfectly normal jobs and have enough money to buy groceries but who get 85% of their food from dumpsters! They've been working with local agencies to get some of this salvaged food to homeless shelters.

There's a shortish sort of documentary called Dive! that explains it all and explains how and why they don't get sick.

I trade other items for meat from a friend of mine who is a hunter. I give him burl wood for his wood projects, which I gather in the hills on my hikes. He gives me frozen slabs of wild game meat. My advice, see if you can trade favors or items for food. Or just ask for food. Many people have some canned food they don't really fancy that much that is just sitting on the shelf. There are also food shelters that will provide meals and food. Not all of it will be paleo but some of it will be decent.

Sometimes you just have to survive the lean times. I had couple years living on bread and mustard with occasional additions of cheap bologna or ramen soup. When you are really poor you do what you can, but some things are just impossible to achieve.

If I were really poor at the moment I would focus on getting a few elements as healthy as possible - tuna, eggs, chicken, ground meat and stretch it as possible with whatever is available. the rest - fillers with whatever they have in food banks that's least unhealthy. I would stay away from grain and sugar, but try to get other foods.

There are soup kitchens that may have some dishes really nutritious or at least not too unhealthy.

I can't come up with anything else that would be practically useful and didn't sound paternalist or insensitive.

Roadkill! There's a guy on Youtube who lives off animals recently killed on the road. Sounds grim, but a good source of meat. He eats lots of badger, even odd things like owls. I believe he also freezes them.

Gardens can be a relatively inexpensive way to get some vegetables. Even though the weather is cooling down there are some vegetables that thrive in cooler climates, like lettuces, spinach, and brussels sprouts. Also, most communities have classes to teach you how to forage wild plants safely.

this sounds really weird, but you can ask your friends to save their bones for you. Just tell them to stick them in a zip lock in their freezer. When the zip lock is full, you take the bones off their hands. Making stock out of bones is a great way to get nutrients without having to buy meat.

My favorite book on foraging is this one: "The Forager's Harvest" by Samuel Thayer http://www.amazon.com/Foragers-Harvest-Identifying-Harvesting-Preparing/dp/0976626608/ref=sr_1_1?ie=UTF8&qid=1295718333&sr=8-1 It is organized by season. So flip to the current season to see whats out there and what it looks like in the season you are currently in. He tells you where to find it, what it looks like, other things it looks similar to that are dangerous, and how to prepare it. He also tells you whether it is flavorful or just useful for survival. This book is great and I've used it some to forage.

If you don't have money to buy it, try swap.com you can list books/cds/dvds/games you don't want anymore and swap with someone who has what you want and you have what they want. All you have to pay is to ship your item to them.

Also look into getting into wild mushroom foraging if you are in an area that supports it. I have a friend from Oregon who collected morel mushrooms and sold them and made good money doing it. You might be able to swap mushrooms with a nice restaurant in exchange for bones or meat.

Also, I've found that supermarkets that cater to certain cuisines have those food staples for cheaper prices. Whole foods doesn't have any coconut oil for less than $8 a jar. The local Indian grocery store has it for $3.00.

Oh, and also look for weird cuts of meat at the grocery store. I saw a beef tongue that weighed over 2 pounds and only cost $3.00. That's lots of meat for the money.

I totally agree with dumpster diving too.

Get into the wilderness and hunt/forage...

Potatoes (without skin) and sweet potatoes are quite inexpensive and much better carb sources than grains. If you combine it with some inexpensive but nutritious meat cuts (bones could even be free in some areas) you would have a basic grain and legume free diet. You would still need some fish meat to complement, perhaps from canned fish.

economically disadvantaged = poor.

Many farmers markets accept food stamps. Even if you don't have food stamps, this may be a way to get good fresh vegetables and lean grassfed meats. As you shop, strike up a conversation with the farmer (they love talking about their farms!). As you develop a relationship with the farmer, possibly over several visits, you can find out what they do with the bones, organ meats etc. after slaughter or what they do with "ugly" produce -- the stuff with blemishes, slightly wilted etc. They may be willing to sell it to you at a greatly reduced price, especially if you discuss your financial situation with them. Also, if you've been buying food with food stamps from them, they will know that you are really in financial need. I have a farmer who saves her "ugly" apples for me, and a friend who works on a farm who salvages food from the "scrap pile" for her family and her friends' families--stuff that probably wouldn't sell in a grocery store but is still nutritious.

The WIC program has also greatly expanded its nutritional choices and offers fresh vegetables and canned meats now. If you are a pregnant or nursing woman or have children 5 years old and younger, you could get a lot of generally healthy foods--some Paleo and some not too bad nutritionally, like brown rice and peanut butter.

Offal is stupidly cheap. Heart meat even has a very similar taste/consistency to normal muscle meat.