Walking into your average supermarket is a lot like being a contestant on “Jeopardy!” If you think hard, choose wisely, and give all the right answers, you can go home with a carload of cash and prizes. But make a few mistakes and you'll leave with an empty wallet—not to mention a lot of empty calories.

In fact, even the lowest-priced supermarket in your neighborhood is brimming with complete rip-offs—health foods that aren’t healthy, gourmet foods that aren’t gourmet, specialty items that just aren’t that special. Here are just some of the foods you're overpaying for, compliments of Eat This, Not That! Supermarket Survival Guide and Cook This, Not That!.
Organic Onions and Avocados
The Environmental Working Group, an organization that studies pesticide contamination, ranks onions and avocados as the most pesticide-free vegetable and fruit, respectively—even when grown conventionally. 

In fact, as a general rule, anything you have to peel before you eat (such as bananas or garlic, for example) is relatively low in pesticides. If you want to eat organic, splurge on produce with permeable or edible skin, such as peaches, lettuce, and apples.

Does a bag of Funyuns look like a bargain to you? At about $4, it holds 6.5 ounces of snackable corn inside. Now consider this: a large ear of corn will run you about a buck and weighs just over 5 ounces. So the Funyuns bag contains the food equivalent of 1¼ ears of corn. Do the math here: If an ear of corn costs a dollar, a bag of Funyuns should run no more than $1.25, and that's under the assumption that cheap fillers like sugar, corn starch, and soy flour haven't driven the cost down significantly (a very generous assumption, indeed). Part of the reason this bag contains so little actual food is that it contains massive amounts of air. The corn is puffed and the bag is puffed—so you’re buying mostly puffery. Even a regular bag of potato chips, which is by no means a bargain, contains more actual food than this. A bag of Ruffles is 10 grams, a bag of Doritos 17.

A pound of swordfish can cost more than $20. Why? Supply and demand: Because it’s scarce, it’s viewed as a luxury. But you should consider its high cost a blessing: It probably has saved your family from slow, steady infusions of poison. Due to abnormally high levels of mercury, the Monterey Bay Aquarium recommends that children and women (who could potentially become pregnant) cut swordfish from their diets entirely. A better seafood option: halibut. It has all the flavor, with 40 percent fewer calories, a much lower cost, and it’s one of the cleanest fish out there.

Gluten-Free Baked Goods
Gluten-free foods generally cost two to three times more as their gluten-containing counterparts, and unless you’re among the less than 1 percent of people with celiac disease, there’s no point in coughing up the extra dough. Gluten-free pastries and breads don’t necessarily have fewer calories or more nutrients than regular products. A 2006 study published in the American Journal of Gastroenterology followed a group of gluten-free dieters with celiac disease for 2 years and discovered that 81 percent of them actually gained weight.

5-Hour Energy
There’s a lot of hype in this bottle, but the only ingredient that provides any significant energy is caffeine, of which there are 135 grams in each bottle. That’s less than you’d find in a14-ounce cup of coffee (Dunkin’ Donuts 14-ounce medium has 164 grams of caffeine). Cost for a cup of coffee: A buck or two. Cost for 5-Hour Energy: Between $3 and $4.

Tenderloin Steak
This is consistently one of the most expensive cuts of beef, but all you're buying is a little bit of tenderness. In fact, tenderloin isn’t a particularly flavorful steak. So why does it cost so much? Because there aren’t many tenderloin steaks on a cow. Switch to top sirloin instead. It’s one of the leanest cuts on the cow, and it packs in far more rich, deep, beefy flavor. And depending where you’re buying, it might end up costing you about half as much. This saves you cash at the supermarket--and the steakhouse!

Anything with a Cartoon on the Box
You know there's trouble when food needs a mascot. A grinning cartoon character on the front of a box is a surefire sign of two things: 1) The box is filled with mostly cheap carbohydrates, and 2) Most of the money you spend on it will end up in the pockets of marketers. See the Golden Crisp box here? The mascot on the front is known as Sugar Bear, which explains why more than half the calories come from pure sugar. And what's that all around him? Advertisements. This box is like a big billboard stuffed full of junk that will make you flabby. You might as well just eat your money—at least that's sugar free.

(c) David Zinczenko with Matt Goulding