Cheapest by far is by Airtrain/subway ($7.25). Take Airtrain from your terminal to Jamaica Station. Take the E subway (white letter E in blue circle) to 42nd St. Get off there and follow the signs to transfer to the 1,2,3 subways (white numbers in red circle), take the uptown 1,2 or 3 subway to 96th St. Walk two blocks south on Broadway to 94th St. and turn left.
Cheapest by far is by