For decades, Brad and Heidi Stokes have put health care at the center of every important life ­decision.

Heidi Stokes, whose lupus was diagnosed when she was a teenager, picked her early career path around jobs that offered medical benefits. Husband Brad developed a rare liver disease in the late 1980s and has since had two liver transplants. Their college-age son, Christian, was diagnosed with diabetes when he was 15 months old.

As small business owners with complex medical needs, the couple have had only one realistic option for insurance coverage: the state’s high-risk pool. But that will change Tuesday with the debut of the MNsure insurance exchange, an online marketplace that gives individuals and small businesses a range of choices while using the power of competition and federal tax breaks to hold down costs.

“The idea that we could go shopping for insurance — and select something for ourselves — is just unbelievable,” Heidi Stokes said. “For the first time, I’ve got some hope for the future.”

MNsure and other state exchanges across the country are a critical element of the federal health care law known as Obamacare. Even as controversy continues to rage around the law, its final rollout in the coming months will bring a sharp change in how millions of Americans pay for health care.

While most people will still get insurance through an employer, those who shop on MNsure will decide for themselves which insurance company to use, how much coverage to get and what they’re willing to spend.

“What we’re seeing Oct. 1 is a reset button,” said Geoff Bartsh, a vice president with Medica. “Everyone is setting the table in a way where it’s easy to see what’s out there, what’s available and what the trade-offs are.”

Consumers visiting the MNsure website will be able to weigh various elements that matter to them, such as premium prices and whether their doctors or medications are part of a certain plan. They can shop online on their own, work with insurance agents, enroll directly with insurance companies or call a toll-free number for help.

Choosing a plan will require setting priorities. Lower premiums might mean higher copays, or a smaller network of physicians that might not include favorite doctors or hospitals. PreferredOne, for example, offers an open network of almost all Minnesota doctors and hospitals or a lower-cost network that consists mostly of the Fairview, HealthEast and North Memorial systems. Choosing the latter would mean paying more to see doctors at out-of-network places such as the Mayo Clinic.

Advocates say it’s different from the HMO movement of the 1990s, which consumers viewed as an invasion of their personal choice of doctors. After two decades of skyrocketing health prices, consumers are ready to make tough decisions between lower insurance costs and larger doctors’ networks, said Steve Peterson, PreferredOne’s marketing director.

“Think ahead of time,” he advised. “Would I be willing, if I could save a certain amount of money, to change” doctors?

MNsure leaders are confident that people who buy music on iTunes and bluejeans at will figure out how to shop online for health insurance once they try the exchange.

Advocates and MNsure officials have tried to ready Minnesotans for the choices ahead, using town hall meetings and an amusing commercial campaign about the value of health insurance featuring Paul Bunyan and Babe the Blue Ox. But many people still aren’t familiar with the term MNsure or don’t understand the concept.

Seniors already covered by the Medicare may not know that it isn’t for them. Some people believe they will be forced to use the exchange, while others think it is going away because of the political standoff over Obamacare. Some believe MNsure itself is an insurance plan, rather than an online marketplace.

“MNsure?” asked a Coon Rapids woman who recently lost her workplace health benefits and will likely need to use the exchange. “Is that that Obamacare insurance?”

Still, MNsure is expected to be a key avenue to insurance coverage for many of the 500,000 uninsured Minnesotans, which proponents said is unparalleled.

“The system is bigger than anything I expected would ever happen in my life or at least in my career in health care, which is about 40 years or so,” said Deb Holmgren, president of Portico Healthnet, a St. Paul charity that for years has connected poor Minnesotans with health care and insurance. “It will have a major impact on that group of people who for years have been left out” of the traditional health care system.

The success of MNsure, and exchanges across the country, will depend on how easy they are to use and whether they give consumers answers in an easy-to-digest format, experts say.

“Comparing premiums is pretty easy,” said Robert Krughoff of Consumers’ Checkbook, a Washington, D.C.-based nonprofit that provides plan comparison tools for federal employees. “But trying to decide, say, between a plan that has a $200 deductible and $10,000 out-of-pocket limit and another that has a $1,000 deductible and $3,000 limit is a mind-boggling question for consumers. It’s mind-boggling for brilliant economists.”

And yet some local consumers said they already have a pretty good idea of the trade-offs they will make.

Dylan Fresco, an independent artist, said his priority is a lower deductible. He would pay a higher premium if he could find a plan on the exchange with a deductible lower than his current $5,000. The Minneapolis man said he worries all the time about one injury forcing him to pay the full deductible of his current plan and exhausting his bank account.

“I’m OK with copays,” he said. “I’m all right with throwing down $30 to see a doctor. But having that sense that, if one thing happens, I’m out such a large chunk of money, it leads to more worry and concern.”

Terri Adams of St. Paul just wants any insurance as soon as possible for her 17-year-old son, Malik Curtis, to provide preventive care and cover him in the event of an accident. Adams has insurance due to a disability through the federal Medicare program but can’t afford premiums to cover her son.

The expansion of public benefits under the health care law should qualify him for a state-subsidized health plan with premiums that Adams can afford. For now, she worries every time Curtis, a tailback for the St. Paul Central High School football team, carries the ball and disappears into a crowd of tacklers.

“They all pile on him so I don’t barely see him,” Adams said.

The last event with such sweeping scope and impact on the health care of so many Americans was the 2006 launch of the Medicare Part D prescription drug benefit for seniors. But Part D was phased in gradually. Seniors went from having no prescription drug coverage to discount cards before they had to go online and select Part D drug coverage plans.

The process also was a bit simpler, said Jean Wood, executive director of the Minnesota Area Agency on Aging. Seniors basically wanted to know which plans covered their drugs at the lowest cost; whereas people using MNsure will have to weigh the premiums of plans with other costs and coverage limits and the doctors that are in the plans’ networks.

Heidi Stokes and her family already sense the complexity of decisions ahead, even as they cross their fingers that Obamacare will deliver as advertised.

With all three family members dealing with long-term, chronic illnesses, they set aside nearly $22,000 each year to buy insurance. They drive cars “until they drop,” take short vacations in fear of a medical crisis and have put less money into retirement savings.

The couple, both 54, own a small production studio business in the downtown Minneapolis Warehouse District, Aaron/Stokes Music and Sound. They provide medical coverage for their employees even though they can’t get on the plan themselves.

The two must wade through a number of options once the exchange launches: Will they include themselves in small-group coverage? Continue to buy a separate family plan? Or will their employees be better off shopping MNsure themselves with a company contribution?

The couple is hopeful for the new world, yet wary.

“We will do anything — make any sacrifice — to pay for insurance,” Brad Stokes said. “All I know is something had to be done.”