Really depends on how you wish to travel.
Public vehicles, hostels drastically reduce costs.
Bangladesh, Vietnam, Cambodia are cheap compared to other countries.
Vietnam is the best and cheapest destination you can travel from India. Direct flight from Delhi and Kolkata. Checkout my Vietnam video in my tripoto account to get a feeling how Vietnam looks and feel a lot better than other nearby countries.
Here are some of the cheapest countries you canvisit from India:-
1. Vietnam
2. Cambodia
3. Nepal
4. Bhutan
5. Sri Lanka
6. Thailand
7. Kenya
8. Taiwan