Don't charge more than your state's maximum notary fee.
You can always charge less, but don't charge more than your state's maximum notary fee for notarizations. Travel fees and waiting fees are separate though. Set fees for loan signing are different too since you are being paid for supervising the signing of primarily non-notarized documents. You can look up your state notary fees by clicking on your state on the find-a-notary page of 123notary.com.