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A little research can save you a lot of cash on prescription drugs, according to a secret shopping study by Consumer Reports.

The magazine called more than 200 pharmacies across the country to request retail prices for five best-selling drugs: The diabetes drug Actos; the antidepressant Lexapro; the cholesterol-lowering pill Lipitor; the blood thinner Plavix; and the asthma treatment,Singulair; all of which are available as generics.

Depending on the pharmacy, costs varied by as much as $749 for a month's supply of all five drugs.

"A consumer can't assume that the price of their prescription medications is set in stone," Lisa Gill, prescription drugs editor for Consumer Reports, said in a statement.

A person without insurance could pay as much as $150 a month for generic Lipitor at CVS, compared to just $17 at Costco, the study found.

"Big-box stores such as Costco and Walmart use the pharmacy as a traffic builder for their stores, whereas traditional chain stores, such as CVS, Rite Aid, and Walgreens, make the majority of their revenue and profits from the pharmacy," Stephen Schondelmeyer, a professor of pharmacy economics at the University of Minnesota, wrote in the report.

A spokesman for CVS took issue with the study, telling ABCNews.com in an email that "pricing surveys do not accurately reflect what most pharmacy customers pay for their prescriptions given various value, discount and third-party insurance programs."

Independent pharmacies had some good deals, too. But their prices varied widely from $131 to $1,073 for all five drugs.

"One of the big takeaways is that you have to ask for the best price and see if your pharmacist will work with you. Especially for the independent pharmacies, if they want to retain your business and loyalty, they will help you get the best price," Gill said.

Click here to read the report. And read on for more tips for saving money at the pharmacy:

Go With Generics

Choosing a generic instead of its brand-name relative can save you thousands of dollars a year, according to Gill.

"If your doctor prescribes Lipitor, you may be taking it for the rest of your life. So it can really pay to shop around," she said. "Talk to your doctor about lower cost alternatives in the same class of drug. And make sure you have that talk when your doctor is about ready to write the prescription. Once you're taking a drug and tolerating it well, your doctor might be less inclined to try alternatives."

Aim Low

Shoppers weren't always given the lowest price, Consumer Reports found. It never hurts to ask the pharmacist for a better deal.

Ditch the City

Some urban pharmacies had higher prices than rural ones, Consumer Reports found. A month's supply of generic Actos at a pharmacy in Raleigh, N.C., cost $203 compared to $37 outside the city.

Load Up

Some pharmacies offer discounts on a three-month supply, so ask for a 90-day refill.

Do Your Homework

Big-box drugstores and pharmacy chains offer discount generic-drug programs, which can land you some generics for as little as $4 a month, Consumer Reports found. Just make sure to check the fine print.