Our tale begins with Stuart Shapiro going to his local drugstore to get a prescription filled for the blood-pressure medicine Vasotec. The pills aren't for Shapiro. They are for his dog, Charlotte. Don't laugh.

Charlotte is a 7-year-old Labrador retriever suffering from a bout of Lyme disease. The Vasotec was prescribed to stop kidney damage. Because the medication is for Charlotte, the pills aren't covered by Shapiro's health insurance. He has to pay for them out of his own pocket. He's in for a big surprise.

At his first stop, his local Eckerd drugstore, they tell Shapiro that a 30-day supply of generic Vasotec will cost him $118.39. Woof!

Shapiro decides to call around to other drugstores. He dials up CVS. There, the Vasotec will cost him $138.99. He calls Rite Aid. Their price is $92.99. Finally, he calls Wal-Mart. They sell him a 30-day supply of Vasotec for $31.54. Woof!

Shapiro, by the way, is not an amateur at this game. He is a physician, who served as Philadelphia's health commissioner in the 1980's, under Mayors Bill Green and Wilson Goode. "I was truly astounded when I got the price at Wal-Mart," he said. "I wouldn't have believed it if I hadn't made the calls myself."

SHOP AROUND

The pharmacist at Eckerd didn't believe it, either. Shapiro went there because the chain has a policy to match the lowest price available. The Eckerd pharmacist called the Wal-Mart, confirmed the $31.54 and gave Shapiro the Vasotec at that price.

Moral of the story: It pays to shop around--especially if you are among the millions of Americans who don't have health insurance plans that pick up most of the cost for prescription drugs.

Following Shapiro's lead, I checked around at Philadelphia-area pharmacies and found variations as high as 30 percent on prices for popular drugs. For instance, the price for Nexium--the little purple pill for chronic heartburn--ranged from a low of $121.32 at Wal-Mart to a high of $155.99 at CVS.

A 30-pill supply of Vioxx, an arthritis medicine popular among seniors, cost $103.99 at Walgreens, compared with $85.78 at Wal-Mart. Generic Buspar, an anti-anxiety drug, ranged from $23.78 at Wal-Mart to a high of $40.29 at CVS.

Let me put it another way:
If you were an anxiety-ridden person with chronic heartburn and arthritis who needed to take these three medications every day, you would save more than $800 a year by going to the Wal-Mart pharmacy.

This is not a local phenomenon. Last year, New York City's Department of Consumer Affairs surveyed 51 chain and independent pharmacies and found the same variations in prices between drugstore chains.

WHY BOTHER?

In fact, it found variations in prices among stores within the same chain. How can this be? Alan T. Sorensen said it is an example of something economists call "consumer search". Some people will search for the best price, but most don't want to invest the time. This enables stores to set an "optimal price".

Sorensen is an economist at the University of San Diego who has researched drug prices. By the way, Sorensen was surprised when I told him Wal-Mart had the lowest prices on the drugs I sampled. He said his research--more extensive than mine--found that Wal-Mart and other big-box retailers weren't always cheapest.

Todd Andrews of CVS said mass merchants, such as Wal-Mart and Costco, will lowball on prescription drug prices to get people in the door to buy other goods. Andrews said that chains such as CVS offer other services: convenient locations, longer hours, 24-hour pharmacies--and all these add to their costs.

My advice: If you take three or four prescription meds on a regular basis, or you know someone who does, take the time to call around for the best prices. It could save you mucho bucks.