Which means of transportation is the most economical for traveling all over the country?

The most economical mode of transportation depends on your travel route.

If your travel route involves inter-provincial or cross-national, the most economical choice may be to take the train. Train tickets are cheaper than plane tickets, travel longer and enjoy the scenery better.

If your travel route is only in one province.

Then the most economical choice may be to take a bus or coach.