Vietnam has the perfect combination of being cheap as well as having lots of sights. You can survive with a little money here. If you spend $7 then it is easy to accompany a decent room for a night stay. For $25 you can get the most premier hotel rooms for a night. You can get a Vietnamese meal for $2 and locally brewed beer for $.50.
The beaches of the Vietnam will be over crowded and is not quite good as their neighboring countries. But it is the most fantastic country as you can feel that you are in the different part of the world.
Thailand is supposed to be the expensive country but you should not travel to the south part of Thailand. Just turn your focus on inland regions of the north.
Take a train from Bangkok to Chiang Mai. It will cost around $12. There you can find basic private rooms starting at $8. If you need in midrange then Chiang Mai is the place to get independent midrange hotel rooms. Food around the Thai is delicious and inexpensive. If you eat in a local restaurant you can find some fantastic stir for about $2.50. For any kind of transportation use which is easily accessible.
It is a great destination which is present near Spain. You can easily reach by budget airline from your place or through a ship from Spain. You will find that it is easy to travel in this country for under @30 a day. You can simply order a shish kebab with some salads in one of the street stalls here and you might be charged only under $12. But you can find the same meal at the Moroccan hotel for just $3.
It had been off the trend due to years of political situations, but the country is now stable and open for tourism. It is becoming popular day by day. Currently it is the cheapest location in Central America. Basic private rooms can be found for around $10 per day. Costa Rica is attracted by most of the travellers but it is still a growing tourist destination and lots of activities are here.