HOUSTON -- Local 2 Investigates is looking out for your bottom line at the grocery store.

No matter where you drop your dough, these days you're probably watching every dollar.

Billie Hall budgets by using coupons -- a lot of coupons.

"That's what they call me, the coupon lady," laughed Hall, when we caught her shopping with a thick folder full of coupons she'd clipped.

Unlike Billie, we went shopping without coupons. We bought the same items from five stores to find out where we would get the best deal.

"I believe Kroger would come out on top," guessed Hall.

"I would think H-E-B is probably the least expensive," said another shopper.

The bets are on the table. We shopped at H-E-B, Kroger, Randalls, Super Target and Wal-Mart Super Center.

We bought the same 10 items from each store. They're items you probably have on your grocery list -- milk, bread, Frosted Flakes, granola bars, Kraft Macaroni & Cheese, laundry detergent, tuna, baby food, peanut butter and fruit cups.

Just to make certain no single sale swayed our results, we shopped for the same 10 items at the same stores in August, October and again in November. We averaged the totals to come up with Houston's lowest priced store.

Wal-Mart Super Center came out on top.

The 10 items at Wal-Mart cost us $24.80.

Wal-Mart beat the highest priced store, Randalls, by $6.26.

The same 10 items cost $31.06 at Randalls.

The other three stores came in neck and neck.

The groceries cost us $25.98 at Super Target, $26.25 at Kroger and $27.52 at H-E-B.

Only $1.54 separated the three. It's a savings some shoppers might not even notice.

What we did notice at every store was an increase in the price of items we tracked over four months.

The price of Kraft Macaroni & Cheese shot up 46 percent at Kroger from 54 cents to 79 cents in just two months. The Mac & Cheese increased at every store but Target.

Starkist Chunk Light Tuna in a can jumped 28 percent at Randalls. We noticed an increase in Starkist at every store but Wal-Mart.

And the price of Tide liquid laundry detergent increased by 19 percent at H-E-B from $6.73 to $7.99. We spotted the increase at three out of the five stores.

So what gives? Manufacturers blamed skyrocketing oil prices and an increase in the cost of crops such as corn over the summer.

But Waller County corn farmer Tom Paben said he's not seeing the profit.

"Times are tough right now on the farm," said Paben of a drought and rising production costs in 2008.

Gene Hall of the Texas Farm Bureau said farmers got more than their fair share of blame for the rise in food prices.

"Since then, we have seen both the price of oil and corn drop by approximately 50 percent and yet grocery prices remain very high," said Hall. "We're kind of curious as to why that is."

"My guess will be is suppliers are going to try to hang onto some of that profit for a while, especially in this economic time to help their bottom line," said H-E-B President Scott McClelland.

While H-E-B has already lowered the cost of some store-brand items previously marked up because of gas prices, McClelland said suppliers are still taking.

Take tuna, for example.

"They're moving from a 6-ounce tuna to a 5-ounce tuna," said McClelland, holding up the two cans.

But at the same time, Starkist raised the price H-E-B pays from 69 cents to 84 cents.

"In this instance, the cost went up and the size went down, so it's a double whammy for customers," McClelland said.

If you think that's just small change, consider this -- on average, grocery stores make about 1 cent for every dollar you spend.

It's why stores such as H-E-B watch every penny, studying competitors Kroger and Wal-Mart's prices every month and then adjusting their own.

"On an average month, we look to price 8 percent lower than Kroger and we're just a little bit higher priced than what Wal-Mart would be," said McClelland.

In a statement, Kroger wrote, "Our retail prices are a function of the cost of the product from the manufacturer. In terms of the price comparison, we believe your sample is too small."

Kroger also said its customers save because it triples and doubles manufacturer's coupons.

Randalls e-mailed, "These limited-item price comparisons (yours was 10 items) rarely provide consumers with an accurate picture of real grocery prices with more than 50,000 items in a typical store. In other words, Randalls carries more than 50,000 items in any one of our stores. A comparison of only 10 items does not provide your viewers with a true picture of prices across the entire store nor does it appropriately reflect the full savings that our customers enjoy. During any one week, we have nearly 5,000 items across the store at significantly reduced special pricing. Randalls also provides customers with a broad range of other savings opportunities across the store and at the fuel pump that will not likely be reflected in this kind of story."

Wal-Mart wrote, in part, "We take our commitment to provide value very seriously. We work closely with key suppliers, reduce packaging and lower shipping costs so that we can help keep prices low. When items do increase in price, we have take into consideration many factors, such as transportation and cost of manufacturing."

What you really want to know, though, is when these current prices will level off.

McClelland told us there's a good chance we'll see deflation in retail prices instead of inflation.

E-mail us what you've noticed at the grocery store lately and send in your questions. We'll do our best to get answers and air them for you on KPRC Local 2 at 10 Wednesday night.

And on Thursday at 10 p.m., has it happened to you? You go to the checkout only to be overcharged. Who's looking out for your bottom line?

You can find a lot more information on how to save at Houston-area grocery stores on the Ask Amy blog.

More Information:

Spreadsheet: Grocery Store Price Comparisons