Don't most states have their own calculators? I went to my state's calculator and tried out a bunch of different options to see how varying our income (via Roth ladder) would impact our annual spending. When I applied for coverage through my state's exchange, the cost was exactly identical to what the calculator gave me down to the penny. For my state it took maybe 2 minutes to get an accurate estimate.
Also, if you're not sure about the cost, make sure you fully understand both cost sharing reductions and subsidies and how the various steps work. Just one extra dollar of income can cause you to jump into a significantly higher cost band if you aren't careful. If possible, try to stay just under 150% of the Federal Poverty Level (FPL). If you can't, try to stay under 200%. If you can't do that - stay under 250%. It could cost you thousands of dollars extra each year if you earn, for example, 150% of the FPL + $1.
In addition, make sure you understand not just the premiums you will pay, but also the deductibles, co-pays, and prescription costs.
You may or may not find the same thing that I did, but in my case I was able to drop our household's expected spending by nearly $20k / year by optimizing our income for both health coverage as well as state and federal taxes. That's for 2 people, but it shows how important this is. It probably took me about 5 hours to understand the system well enough to find that savings - that's a pretty solid hourly rate.