Coming to ANA by train? Planning on coming more than once? More than one person? Why don't you buy a multiple trips card and share it with your friends?
Grand-Central / Pleasantville Off-Peak is $9.75 ($13/Peak) but if you buy a 10-trip ticket, you'll be paying $8.30 a ride instead!
Also, it won't save you money, but time...if you're up in Harlem, just go to 125th and hop on the train from the Harlem Station...even faster and easier!