If you can't afford coverage you have a number of options.

First off check out HeatlhCare.Gov and see if you qualify for cost assistance or Medicaid based on your projected Modified Adjusted Gross Income (MAGI). Unfortunately some states have rejected Medicaid, so this makes it extra hard for people in these states.

If you go with a high deductible health plan you can also use an HSA to get some tax benefits and to help lower your MAGI.

If the lowest cost plan costs more than 8% of MAGI you are exempt.

People who are exempt due to affordability (or some hardship exemptions like being denied Medicaid) and those under 30 years old can get a low cost catastrophic plan inside or outside the marketplace.

There isn't always a good answer to not being able to afford coverage, but looking into cost assistance, health savings accounts, Medicaid, and all of your options is going to be your best bet. If everything is still unaffordable, look into exemptions.

Hopefully, other people will post some suggestions below, it's of course not an easy question to answer, and we feel for people finding themselves in this position.