NEW YORK (CNNMoney.com) -- Getting cheaper prescription drugs from Canada just got easier. The Department of Homeland Security won't be confiscating medicine shipped from Canada to the United States. But before you go online, we're going to tell you what you need to know about this policy change.

Even though the Department of Homeland Security won't be seizing medical importations beginning Monday, it's still illegal to import prescription drugs. But this new policy reverts back to the old system, where Customs officials basically turned a blind eye to the practice.

Prescription drugs from Canada are generally 30 to 40 percent cheaper than drugs from the US, according to experts we talked to. Let's look at the potential in savings here.

Lipitor, a commonly prescribed drug to lower cholesterol, sells at U.S. pharmacies for up to $355 for 90 tablet,s while 84 tablets cost about $185 dollars at Canadian pharmacies.

Crestor sells for up to $251 for a three-month supply here in the States while a Canadian Web site sells it for $157.

Consumer Reports estimates Canadian pharmacies can save consumers up to about $230 per prescription.

You can compare prices of drugs by going to pharmacychecker.com. The Web site evaluates online pharmacies from Canadian and U.S. Web sites.

Gabriel Levitt of pharmacychecker.com says the company makes sure a licensed pharmacist is dispensing the drugs and that your medical information is protected.

You can also do your own Internet search for Canadian pharmacies. But before you order anything, make sure they're part of the Canadian International Pharmacy Association (CIPA). This means the pharmacy has a valid Canadian license and must keep your personal information private. Go to http://www.ciparx.ca/.

Of course you have to be vigilant, especially when it comes to medicine. When searching for legitimate pharmacies, here's what you should keep in mind.

First of all, don't trust pharmacies that sell only lifestyle drugs, like Viagra or opiates, says Peter Lurie of Public Citizen. The pharmacy should also ask you to submit a prescription from your doctor.

And of course, make sure there is an address and phone number for the pharmacy. Of course, check to see that they are part of membership organizations like CIPA or the Manitoba International Pharmacists Association (MIPA).

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