As more and more generic drugs flood the prescription medication market, the demand for generic forms of popular drugs like Lexapro (generic: escitalopram) and Lipitor (atorvastatin) has increased exponentially. Generics are, presumably, cheaper and just as effective as their name brand equivalents.

But patients may not always be getting the best deal on the market. A new study shows consumers may be spending more for their medication at CVS and Target than they would at local independent pharmacies or larger corporations like Costco and Wal-Mart.

Consumer Reports oversaw "secret shoppers" who called over 200 pharmacies with requests for pricing on certain medications. The prescription drugs included diabetes drug Actos, antidepressant Lexapro, cholesterol fighter Lipitor, blood thinner Plavix, and asthma drug Singulair, Reuters reported.

By the end of the study, researchers found an overall $749 difference between the pharmacies offering the highest prices and those with the lowest prices. In some specific cases, the differences are drastic. One staggering statistic says a monthly prescription of Lipitor at CVS may cost upwards of $150 while the same prescription at Costco may cost $17, a $133 difference.

One theory as to why prices are higher at nationwide chain pharmacies like CVS and Walgreens compared to pharmacies that are part of a larger corporation like Costco or Wal-Mart is that the larger corporations are just using prescription drug sales to get shoppers in the door.

Lisa Gill, an editor at Consumer Reports, said, "It really comes down to a store's business model. For example, big box stores tend to use their pharmacies as a way to get consumers through the door with the expectation that they'll buy other things."

Consumer Reports did offer some useful tips for getting the best price for your medication:

  1. Request the lowest price: The report showed that shoppers were not given the best or lowest price if they didn't ask first. Don't be shy -- it's the pharmacy's job to provide you with service. 
  2. Ask for generic medication: Don't worry -- the FDA requires that all generics contain the same exact active ingredients in the same exact strength as the brand name versions.
  3. The city may not be the best place to buy your medication: Consumer Report's secret shoppers found that prices were lower in rural areas than in urban areas.
  4. 90 day refills cost you less than 30 day refills in the long run: Most pharmacies offer discounts on 90 day refills.
  5. Shop around for additional discounts: Corporations like Costco offer discount drug programs for people who buy their prescription often.

The full report will be featured in the May edition of Consumer Reports.