Does anyone know of health insurance that is cheaper than ISO or PSI that can waive F1 health insurance? I'm 27.

You may be eligible for Obamacare if you already don't or will not have any kind of health coverage for the remaining calendar year. You'll need to have a social security to give it a shot. Try logging in to the marketplace and see if that works for you. If you fall on the lower income level for the state, then you may have to pay very little/no payment for a very good coverage.