"People that just sort of haphazardly clip their coupons and stroll through the aisle, they're going to save a little, but they're not going to make a huge difference at their bottom line on their grocery budget," said Nathan Engels, who has earned the nickname "Mr. Coupon" for his strategic use of coupons to save.
Engels runs a Web site, "We Use Coupons," that sees the kind of traffic most grocery stores can only covet.
The site got its name from the response Engels and his wife would give when people asked them how they saved so much money at the store.
The 28-year-old from Villa Hills, Ky., spends almost no money on groceries -- and sometimes walks out with a credit. His garage is filled with astonishing quantities of Jell-O, freezers full of veggies, and shelves of shampoo and toiler paper -- all booty from his extreme couponing trips.
"The last time I purchased toilet paper at the store was in 2007," he said, boasting that a three-year supply cost him $30.
To learn the secrets of the couponing world, "Nightline" visited Engels and Jill Cataldo, also known as "The Coupon Queen," who teaches classes in Chicago and writes a nationally syndicated column about coupons.
"Our weekly grocery bills right now for our family of five are between $40 and $60," she said. "And that's everything, pets, child and diapers, everything."
Watch the story on "Nightline" tonight at 11:35 p.m. ET
The Internet has made this new breed of couponing possible. Engels and Cataldo share information on deals on their Web Sites, connecting thrifty shoppers in a nationwide network of supermarket intelligence.
The success of their Web sites has made Cataldo and Engels celebrities of sorts in their communities.
"I can't really go the grocery store too often without being recognized here in Chicago anymore," Cataldo said.
"Nightline" challenged Cataldo and Engels to put their couponing skills to the test to see who could make $50 go further towards their weekly grocery bill.
Cataldo headed to her favorite store, Jewel-Osco and Engels didn't waste any time hitting up Kroger.
Weaving through the supermarket aisles, the experts shared their tips and tricks on how to save big.
Tip #1: Get Paid to Shop
By clipping coupons and looking for special promotions, Engels actually gets manufacturers to pay him to buy their product.
"It's called an overage. It'll be right off my bill at the end," he said, explaining what happens when the coupon's value exceeds the actual price of the product.
The store was also running a special promotion -- buy eight cans of tuna, get $4 off -- so Engels actually turned a profit.
"We don't care about the tuna in this instance because we're getting it for free and then actually we're going to make a little money," he said while loading tuna into his cart.
Cataldo's first stop was the customer service desk. Always on top of a deal, she heard about a sale on diapers, so she called the store in advance to have them save her a box.
"This is the size my little guy wears, so I said, 'Hey, if you have one left, can you hold it for me,' and they're usually great about that," she said.