Buying in bulk can seem like an impossible challenge at first, if you're living paycheck to paycheck. But you can ease into it slowly, bit by bit, and if you resist the urge to spend the money you save on other things, you'll soon be able to take advantage of sales and great deals to save even more. Keep in mind that bulk buying is generally much better suited to staple foods rather than perishables.
Start really small, with just $3 extra. Week 1, instead of buying sodas at work from a vending machine at $1.00 a can or more, buy two 2-liter bottles of soda at the grocery store for $3, take them to work with you, and make them last the week. If you're like most of the people I work with, you've skipped $10 worth of canned sodas and only spent $3.
You have that $7 to start Week 2. You need to buy pasta this week, and macaroni is $.89 a pound. If you normally would use a single pound for the week which would have cost $1.29, buy 3 pounds of macaroni for $2.67, using up $1.38 of the money you saved from the sodas. You still have $5.62, and the store brand of tomato sauce is $.29 a can, instead of the $.44 a can for the name brand you normally buy. Instead of buying 3 cans of the name brand at $1.32, buy 9 cans of the store brand for $2.61, using up another $1.29, leaving you with $4.33. Buy the 2 liter bottles of soda again for $3, and you have $1.33 left over.
Now you're into Week 3. You have $8.33 ($7 + $1.33). You don't need macaraoni again, so that $1.29 is available, and you don't need tomato sauce, another $1.32 available. So, now you have $10.94 for bulk buying. You buy a pound of rice every other week for $.89 a pound. You notice this week that 5 pound bags $.59 a pound, so you get one of those for $2.95, using up $2.06 of your $10.94, leaving $8.88. You normally buy a couple of cans of broth for 2/$.98, but you decide to try the soup base for $2.99, using up another $2.01 of your bulk money, leaving you with $6.87. You decide to try making bean soup as an experiment, Spending $.89 on a pound of navy beans and $.89 on a pound of kidney beans, using another $1.78, leaving you with $5.09. You buy a package of ground turkey and freeze it for $1.39, leaving you with $3.70. Buy your soda and you have $.70 left for next week.
In Week 4, you have the $7+$.70, $1.29 for the macaroni, $.98 for the broth, and you saved $2 on lunches by taking homemade bean soup. That gives you $11.97 to work with. You look at the oatmeal rather than the cold cereal, and discover a big container is on sale for $2.29, with about 2x the servings of the cereal you normally buy for $3.29. Buy two at $4.58, and you've used $1.29, leaving you with $10.68. You glance in the meat case, and discover whole chickes are $.69 a pound. You always passed on them before because it was a lot to spend on one thing, but this time you pick up one for $5, knowing you'll get at least 3 meals out of it, probably saving you $1 a meal, and leaving you with $5.68. You discover that your favorite brand of soda is $1 instead of $1.50, so you buy 5 of them, leaving you with $.68 for next week.
It's Week 5, and you have $7 that you didn't spend on vending machine sodas, $.68 from last week, $.89 because you don't need rice, $.98 because you don't need broth, $2 you saved on lunches by taking bean soup, $3.29 for cereal you don't need, and $3 you saved on suppers by buying a whole chicken. You now have $17.84 for your bulk buying (see how this snowballs?) You need pasta and buy two 2-pound packages of spaghetti for $.89 a pound, $3.56, less the $1.29 you normally spent, using $2.27. You have $15.57, and you check the tomato sauce. The sale isn't as good, but you get 12 cans at $.34 each, for $4.08, less the usual $1.32, leaving you with $12.81. You wander by the frozen meat case and notice that out of season turkeys are $.59 a pound. One of the smaller frozen turkeys, around 14 pounds, is $8.50. You realize you have more than enough to buy it, and you can get several meals out of it, a pot of soup from the carcasse, and freeze enough meat for several more meals. And you STILL have $4.31 left for next week.
In Week 6, you have $7 from sodas, $4.31 from last week, $.98 from savings on broth, $3 you saved by making turkey and bean soup for lunch, $3.29 you saved on cereal, $1.29 on pasta, $1.32 on tomato sauce, and $5 you saved on suppers. That's $26.19 you have available for bulk buying this week, and you still have about 3 1/2 pounds of rice, 3 pounds of spaghetti, 9 cans of tomato sauce, a chub of frozen ground turkey, several meals worth of frozen cooked turkey, some oatmeal and beans, and plenty of soup base. And all you did was start with $3.
Some of you have a lot more room in your budget, and that's great, just apply this in ways that make sense for your circumstances (set aside a certain amount each week to take advantage of good sales). Some of you, though, are already eating the cheapest things you can find. All I can suggest is try to scrape together an extra dollar or two and use it to take advantage of a really good sale to buy extra of something you use. Though I ordinarily frown on ramen soups as lacking nutrition (and the poorer you are, the more you need to be careful of it), eating those once a day for a few days as a temporary measure might be enough to get you that dollar or two. It will still snowball, just more slowly. But it's a tiny amount of effort for the end results.
A quick word on a related subject---the pantry. The poorer you are, the more important it is to have a reasonable amount of food stored. Once you are past the first few weeks and have that bulk-buying money established, start buying a little extra every week in staples and canned goods. Use up older stuff first, but build up some extra. I think everyone should have at LEAST 2 weeks worth of food and water in the house for emergencies, and preferably at least one to two months of food. This can be built up slowly, a bag of beans here, a bag of rice there, a couple of cans of vegetables, $2 - $3 a week, and you can store up a month's worth of (admittedly boring) food within a few months. Even $.50 worth of food stored per week gives you a little cushion.
I've heard this referred to as hoarding, and I'm baffled by that attitude, at least in relation to the poor. If food prices jump up, the poor are going to be hit the hardest (think back about 3 years ago when flour and rice and other staples doubled in price in the US.) This is a kind of food savings account, whether against inflation or against illness/loss of income. I have about 2 months worth in the house and would be happier with 4 (but I lack the space to store it), though I admit by the last couple of weeks, we'd probably be living on things like rice with just a touch of canned chili on top for flavoring. About once a year, we pull out anything that's getting older that we weren't able to eat and donate it to a food bank so it gets used while it's still good. So, in our case, it's also a form of charity.