A few times in my adult life, I have purchased indemnity health insurance. It was basically just in case something catastrophic happened, I wouldn't be on the hook for more than some high deductible. I didn't plan on using it at all, really, which was an easy bet because I was young and healthy. For me, the plan was a back up for a random accident or something similar. (I am still relatively young and healthy and would do it again, actually.)
These purchases of health insurance were all pre-ACA, so IDK what similar plans, if any are available now. I did find them on ehealthinsurance.com.
Good luck!