To Be clear:
The COSAR card is not insurance and doesn't get the person rescued anything except goodwill. If you have a hunting or fishing license or have a registered OHV, you pay a small amount into a Search and Rescue fund. If you don't have one of these things, you can buy COSAR card (sometimes called a hiking license). This fee goes to a DOLA (Dept. Of Local Affairs) fund from which SARs--almost all self funded all volunteer organizations--may apply for reimbursement of expenses of a mission--like gas, bandages etc. The individuals who spend the money may be reimbursed for some or all of their out of pocket expenses depending on a bunch of criteria. Any money left over in the fund is distributed via grants to applying SARs for things like first aid training for members etc. In the end, it is the Sheriff of any county who is on the hook for stuff like choppers. Sometimes,an individual's insurance can cover something like flight for life as a ground ambulance may be covered--or not. The "Rescue" part of SAR is getting the poor SOB who needs help to more advanced care which would be an ambulance, or Flight for life, or maybe the bar.
The Sheriff may try to charge a rescued individual if the individual were a jerk and deserve to be smacked financially. That almost never happens.
For three bucks, just buy a card just to support the fund and hope to whoever you never have to use it