Originally Posted by
guv1976
Unless the train sells out completely, you can buy a ticket at any time before departure -- either on the app, at an Amtrak ticketing location near you, or at the self-service Quik-Trak machines at EWR Rail Station. However, just as the airlines utilize fare "buckets," so too does Amtrak. So a walk-up fare might be higher than one you purchase in advance.
All three passenger terminals at EWR are connected to the rail station via the Newark AirTrain monorail; your Amtrak ticket includes the $8 AirTrain fee, and will allow you to pass through the fare gates at the rail station.
Will you be checking any baggage? If not, I would say allow ~ 45 minutes from the time your plane parks at the gate until your Amtrak departure time.
As Guv1976 stated, Amtrak tickets have dynamic pricing and it is rare to see prices this low so the price today is not what the price may be tomorrow. He has given you the New Rochelle code, make sure to use it. Many times (not always) the first stop for an Acela train after 125th Street in Manhattan is Stamford, Ct. Not all Amtrak trains (and very few Acelas) stop in New Rochelle