Amtrak is as low as $37 per person, each way, though $59 and higher on peak travel times.

You can also check out the bus, which is about the same rate ($38) but not subject to peak rates. I have taken the bus - it's not that bad for a 2.5 hour trip.

Bus website:
http://www.trailwaysny.com/html/english/fares.asp