New Haven, CT to Princeton University buses and trains from $51

Or, see buses and trains from Princeton University to New Haven, CT.
Here are some trips other travelers have found on Routefriend.
$51
4h 7m
1 stop
Amtrak Megabus
$56
3h 7m
1 stop
Metro-North Amtrak
$56
3h 43m
2 stops
Amtrak NJTransit
$63
4h 21m
2 stops
Amtrak NJTransit