Vancouver, BC to Seattle, WA buses and trains from $15

Or, see buses and trains from Seattle, WA to Vancouver, BC.
Here are some trips other travelers have found on Routefriend.
4h 0m
0 stops
3h 30m
0 stops
12h 25m
2 stops
Amtrak Amtrak
5h 45m
1 stop
Amtrak Amtrak