People who pay out of pocket for prescription drugs usually can count on big savings by buying generic versions instead of brand-name equivalents.

But as we learned from a survey that spanned pharmacies across the country, your costs for generic drugs can vary greatly, depending on where you shop and what questions you ask.

Our study took us to 132 pharmacies – both brick-and-mortar and online establishments – to check on the prices of five common generic prescription drugs: fluoxetine for depression; lisinopril for hypertension; lovastatin for high cholesterol; metformin for type 2 diabetes; and warfarin for preventing dangerous blood clots.

Fluctuating prices

Prices for a 30-day supply of those five ranged from a low of $43 at a Costco in Sacramento, Calif., to a high of $296 at an independent pharmacy in Clayton, Mo.

Why the discrepancies? When a drug first goes generic, the maker’s suggested retail price might be 70 percent of the branded version. As competition among generic manufacturers heats up, that price falls to 20 percent to 50 percent of the brand-name equivalent.

People with drug insurance or a safety-net program pay only a co-payment or a negotiated price (typically more for brand-name drugs than for generics), but pharmacies can sell generics to people who lack coverage for as much as they want.

Overall, our study concluded that online pharmacies – particularly those affiliated with conventional stores – and mass merchants tended to charge the least, followed by independents, supermarkets and drug chains.

Consumer Reports' price survey of 132 pharmacies found that Costco stores nationwide generally charged the least for a group of five generic drugs. Customers also don't need to pay Costco's 0 annual membership fee to use the pharmacy.

However, you might find bargains in each category – medications tended to cost substantially less at CVS than at other drug chains – and prices could fluctuate dramatically even within the same chains and the same stores. At ShopKo, for example, prices for the five drugs ranged from $80 in Marquette, Mich., to $150 in Redding, Calif. One independent pharmacy in Denver, Colo., charged more for fluoxetine than the other independents, but less for lovastatin than the vast majority of drugstores that we surveyed.

Cost-cutting strategies

To find out whether generic drugs are more cost-effective for treating your condition than drugs available as brand-name only, check our free CR Best Buy Drug reports at www.ConsumerReports.org/health. If they are, then ask your physician or pharmacist about switching. Next, compare prices by calling pharmacies or visiting their Web sites.

Other strategies to help lower your out-of-pocket drug costs include:

¢ Seek the cheapest form. We found that prices of the same drug might vary substantially depending on whether it’s a capsule or a tablet. Ask your pharmacist to match lower prices. This makes sense if you want to stick with one pharmacy, which might reduce the chance of taking incompatible drugs.

¢ Buy in bulk. Ask your physician to prescribe 90-day supplies of your medications, which typically cost much less than the 30-day supplies that are often prescribed.

To quickly compare prices and order prescription medications at online pharmacies and other drugstores, consider our free Shop Online service, also available at www.ConsumerReports.org/health.

Just click on the Consumer Reports Medical Guide, find your drug and then click to compare prices and shop online.

– Visit the Consumer Reports Web site at www.consumerreports.org.