Cheapest is by AirTrain/subway ($7.25); take AirTrain from your terminal to Jamaica Station, transfer to E subway to 7th Avve/53rd St, transfer to the uptown D subway to either 161st St/Yankee Stadium (Sherman Ave is about 5 blocks east) or 167th St/Grand Concourse (Sherman Ave is one block east), depending on your location on Sherman Ave.
Cheapest is by