Define acceptable standard of living. In a lot of developing countries, you pay a significant premium to get the lifestyle and safety levels that an American or European expat expects. Luanda, Angola routinely hits the top ten most expensive cities to live in if you've got US/Euro standards. (average monthly rental of a 'luxury' 2 bedroom home- $7,000 US, and a fast food meal will set you back $17.50 US)
Cool Infographics - Blog - Top 10 Most Expensive Cities to Live In*2010
In the US, there are any number of dirt cheap small towns in the Great Lakes/Great Plains region, and many very affordable options in bigger cities like Tulsa.
Overseas, Panama is supposed to have a quite nice standard of living for a reasonable price, and they cater heavily to US expats and the social security checks they bring with them.