Here are the cheapest alternatives:
>Airtrain from your terminal to Jamaica Station, take E subway to 53rd/Lexington, transfer to the downtown #6 subway to 33rd St., walk south on Park Ave. to 31st. or stay on the E subway to Penn Station and walk crosstown on 33rd or 32nd from 7th Ave. to Park Ave. Cost is $7.25 for Airtrain/subway.
>Airtrain to Jamaica as above, take LIRR to Penn Station (faster than subway, trains have overhead racks) and walk crosstown as above. Cost is about $13.
Here are the cheapest