Most of the South East Asian countries are considered budget friendly destinations but again it completely depends on which part of the country you're travelling to and how much you spend on flight fares, hotels, etc. For example, if you take Thailand, not all places in Thailand are cheap. You have to choose a place in Thailand which fits your budget. The same goes for Bhutan - it's cheaper by road from Kolkata than flight but time consuming so you need to decide accordingly what is best for you.