OP: Depending on when you arrive at EWR, you might be able to save several dollars by taking the NJTransit Route 62 bus from your terminal to Newark Penn Station, instead of taking the AirTrain to EWR Rail Station. The bus fare is only $1.60, and the trip from the airport to Newark Penn Station takes about 15-20 minutes.

Google "NJTransit Route 62 PDF" to see the bus schedule. NJ Transit also has a "My Bus Now" bus tracker

https://mybusnow.njtransit.com/bustime/home.jsp​​​​​​

that would let you see exactly when the next bus to Newark Penn Station would depart from your terminal. You could check that once you were off the plane to help you decide whether to take the bus or the AirTrain.

I wouldn't consider the bus if it meant missing an earlier train to Manhattan. But if you're going to end up on the same NJTransit train anyway, the bus is a reasonable option.

By taking the bus, you could get from EWR to Great Neck for $16.10, total (about $8 less than if you used the AirTrain).