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WOODLAND PARK, Colo. - GOP contender Rick Santorum had a heated exchange with a mother and her sick young son Wednesday, arguing that drug companies were entitled to charge whatever the market demanded for life-saving therapies.

Santorum, himself the father of a child with a rare genetic disorder, compared buying drugs to buying an iPad, and said demand would determine the cost of medical therapies.

"People have no problem paying $900 for an iPad," Santorum said, "but paying $900 for a drug they have a problem with - it keeps you alive. Why? Because you've been conditioned to think health care is something you can get without having to pay for it."

The mother said the boy was on the drug Abilify, used to treat schizophrenia, and that, on paper, its costs would exceed $1 million each year.

Santorum said drugs take years to develop and cost millions of dollars to produce, and manufacturers need to turn a profit or they would stop developing new drugs.

"You have that drug, and maybe you're alive today because people have a profit motive to make that drug," Santorum said. "There are many people sick today who, 10 years from now, are going to be alive because of some drug invented in the next 10 years. If we say: 'You drug companies are greedy and bad, you can't make a return on your money,' then we will freeze innovation."

Santorum told a large Tea Party crowd here that he sympathized with the boy's case, but he also believed in the marketplace.

"He's alive today because drug companies provide care," Santorum said. "And if they didn't think they could make money providing that drug, that drug wouldn't be here. I sympathize with these compassionate cases. … I want your son to stay alive on much-needed drugs. Fact is, we need companies to have incentives to make drugs. If they don't have incentives, they won't make those drugs. We either believe in markets or we don't."