Pharmacies may be contributing to the overwhelming costs of prescription drugs, as a consumer investigation revealed that some pharmacies are marking up drugs by as much as 2,000 percent.

For instance, Enalapril, the generic equivalent of Vasotec, a widely prescribed high blood pressure medication, costs pharmacies about $5 for a month’s supply. Yet Eckerd drugs charges as much as $68 for the same prescription, and Walgreen's charges about $60.

Another example is Famotidine, a generic equivalent of the well-known acid reducing medication Pepcid. Famotidine costs your pharmacy about $6, but sells for $97 at CVS and $98 at Rite Aid.

Also consider Fluoxetine, the generic equivalent of the anti-depressant drug Prozac. While your pharmacy pays about $4 for a month's supply, CVS will charge you $79 and Rite Aid will charge you $82.

Investigators found that reasonably priced prescription drugs could be found at stores like Wal-Mart and Kmart and prices were particularly low at Costco stores.

Costco Wholesale Corporation charges $12.97 for Enalapril, $12.24 for Famotidine, and $9.63 for Fluoxetine. Company officials say they still make a profit even with their low prices.

Although Costco usually requires a membership to shop in their stores, the pharmacy can be used with no membership, either in person or online). They can also be reached at (800) 774-2678.

Dr. Mercola's Comments:

I am fond of telling patients that once you shop at Costco you hardly ever go back to Sam’s Club. From the moment you park your car in the stalls that are nearly 50 percent bigger than at Sam’s Club, you know you are in for a treat. Nearly every time I walk into a Costco I marvel at their commitment to excellence at all levels. Their refund policy is outstanding, and I have always received prompt and courteous service there. I marvel at their efficiency and ability to provide such amazing, cost-effective prices on many major consumables. While you will want to take a pass on most of their food as it is highly processed, they do have some food that is worth getting. Particularly noteworthy is their lamb, which is grass-fed and from Australia. It is also important to note that you can use Costco’s pharmacy without being a member. However, I would have a hard time imagining a family that wouldn’t benefit from having a membership (assuming they lived near a Costco).