Medishare is a healthcare sharing program designed for Christians.
Is there any reason a Jew wouldn't be able to join such a program?
As far as I understand it, the program works in such a way that people in the program help pay for each other's medical bills. Therefore, you would be sometimes paying for medical bills of Christians and they would be sometimes paying for you. Somehow it works out to be cheaper than many insurance plans. If you need more info on how it works, it is explained here.