Some plans are still not on the exchange, for some reason. Last year I heavily researched the websites of all the insurance companies that service my county, while there were all those healthcare.gov problems, because I wanted to be able to compare the plans and costs. Once the gov site was up and running I noticed that there were several plans I could see on insurance company sites that were NOT on the exchange. I ended up buying off the exchange because one of these plans suited me and was cheaper than any similar plan on the exchange. [Caveat: if you expect to be able to qualify for subsidies at any point in the year, do not buy off the exchange, as you will not be able to claim subsidies for anything purchased off the exchange. But if your income is too high to qualify for subsidies anyway, I don't believe that it matters.]
This year, I expected that all the plans would be on the exchange. Nope. My plan is still not there, and it still seems the best choice for me, so I guess I'll be buying off the exchange for another year. For reference - I am in a Humana plan which is HSA compatible and has a national network. The Humana plans I see on the exchange that are low cost are all very restricted HMO networks. So, I would also check the websites for the insurance companies in your area, as you never know what you'll find.
