That only leaves a bicycle or running.
With the exception of walking, cycling is the cheapest means of transport.
the cheapest transport is Waterways
I think train
bus
Because it is the cheapest way of transport.
The cheapest bus transportation from St. Louis to Washington DC would be taking the MegaBus. Tickets for a MegaBus can start as low as $1.
Because it is the cheapest way of transport.
Coach or bus.
Shanks' mare.
Transit Van Shuttle Services
Backpacking it, staying in hostels and using the slow trains for transportation makes for the cheapest travel around Europe.
U Haul!