Lonelyplanet.com has a list of the best travel destinations that offer value for money.

Bangladesh tops the list as the cheapest place to travel to on a budget. This budget travel destination offers amazing meals for under US$ 1 and a mid-range hotel room for much cheaper. A traveler can expect to pay about US$150 for a tour at the Sundarban National Park. First-class river cruising for 27 hours at this budget travel destination can cost about US$ 15.
Nicaragua, in Central America is another travel destination that provides good value. The most expensive thing at this travel destination would most probably be the US$ 32 departure tax that one needs to pay when flying out of Nicaragua.
Syria is an excellent value travel destination. One can expect a daily budget of $50 on a mid-range bracket in Syria.