The World's Cheapest Destinations is a guide to the best travel values on the planet. It provides an overview for 21 countries, with activity descriptions and actual prices. Revised second edition.
There's some useful stuff here if you're looking for a basic guide to places in the world that your money will go a long way that are also safe and interesting. I can't get over the fact that it is virtually impossible to keep up to date with geopolitical events that upset both the safety ratings and relative costs of these places.
Turkey, for instance, is an honorable mention in Europe in this book. Well, I'd love to go but US travelers are currently barred from entering Turkey (same for Turks here).
Skim the list and then read travel blogs or podcasts. This author, in fact, was recently interviewed by "Extra Pack of Peanuts" and it was a better, if briefer, look at cheap international travel.
This book has lots of wonderful suggestions that sound workable but I just think I'm past the time of using squat toilets in places I wouldn't feel quite safe. Really made me want to travel again, though!