On the other extreme, if the 40-year-old lived in Jackson, Mississippi, he'd see a 23.7 percent decrease in the price of such a plan, from $405 per month to $309. After subsidies were factored in, he'd also be paying $1 less out of pocket, from $209 per month, to $208.  While double-digit percentage changes are occurring in premium prices for 2015, multiple analyses suggest that the average returning Obamacare customer is likely to face premiums that are higher by about 6 percent or less.  Kaiser looked at the prices of the lowest-cost "bronze" Obamacare plans in the same 48 cities for the same hypothetical person, and found they were increasing by an average of 2.7 percent. Bronze plans cover about 60 percent of medical costs.  After subsidies are factored in, bronze plans in those cities increase an average of 3.1 percent, Kaiser said.  Read MoreObamacare sign-ups seen 30% lower than forecast  But not all people get subsidies.  Former Major League Baseball executive Mark Gorris, a 59-year-old who lives in St. Louis County, Missouri, told CNBC that he recently received a letter from Coventry, the health insurer that sold him a "gold" plan on HealthCare.gov for this year, and was told that "our benefits ... will remain the same, but our monthly premium will rise 22.3 percent beginning Jan. 1." Gold plans cover about 80 percent of medical costs, on average.  "I call our insurance company to see if there was a mistake and they said there was not, this is the way it is and we are free to move our insurance elsewhere," said Gorris, who had been paying $1,361.44 per month to cover himself and his 61-year-old wife Diane. "A rather cold response to a sensitive issue."  Gorris said, "I about fell over," when he heard he'd have to pay $1,665.14 per month. "It felt like a bait and switch."  Gorris said he planned to wait until Saturday to see if he could get a better deal from insurance plans sold on HealthCare.gov, the federally run Obamacare exchange that serves two-thirds of the country.  But he was surprised to hear from a reporter that HealthCare.gov enabled the ability to window-shop for 2015 health plans last Sunday. A quick check of that site showed several gold plans that were hundreds of dollars less than what Coventry was asking him to pay next year for his plan.  Rohan Hutchings, a spokesman for Coventry's parent company, Aetna, said: "Firstly, I am sorry that one of our members had an unhelpful experience recently. We aim to be as helpful as possible and to try and simplify what can be a confusing time for members."  "Our goal is to offer competitively priced products at a rate that will allow us to cover the cost of doing business and offer our customers high-quality products that meet their health-care needs," Hutchings said. "Ultimately, we believe the rates we are filing for 2015 will be competitive with the products offered by other carriers in the marketplace."
HealthCare.gov allows window-shopping on Obamacare plans that go on sale Saturday, and data suggest that price increases, if any, will be modest.