Is there a good ( and cheaper) solution to this until she finds another job that will pay Health Insurance?
I missed this part in the original posting. How long does your wife want to quit before starting a new job? Since this is in the Post-FIRE section, I had assumed she was quitting altogether, but now I realize this isn't the case. You might want to have your posting relocated, like the Ask a Mustachian section or similar.
If it's just a couple of months, then Cobra sounds like a decent option. Keep in mind that with most companies, health insurance is active for the full month that you quit. If her last day is on the 1st of the month, then she'll usually be covered until the 30th or 31st, so that could save some money.
If she'll be out of work for more than a year, then perhaps she can quit in January, so it'll just be your 90k income in the MAGI calculation, which qualifies your family for insurance subsidies.