Trenton, NJ to Princeton University buses and trains from $28

Or, see buses and trains from Princeton University to Trenton, NJ.
Here are some trips other travelers have found on Routefriend.
$28
3h 58m
1 stop
NJTransit Megabus
$53
3h 24m
1 stop
Amtrak Megabus
$64
2h 25m
2 stops
Amtrak NJTransit