Considering the 193 recognized countries of the world and two UN non-member observer states (Vatican City and Palestine), I can easily answer this question with mathematical analysis. I’ve assessed the level of development for each country using the Human Development Index rankings and combined that with average monthly expenses using the Cost of Living Index.
Here are the ten countries with the best balance of monthly expenses and development. Some of these have safety issues, but the question makes no mention of safety.
1.) Kazakhstan (31st cheapest, 51st most developed)
2.) Turkey (30th cheapest, 54th most developed)
3.) Belarus (41st cheapest, 53rd most developed)
4.) Palau (44th cheapest, 50th most developed)
5.) Georgia (36th cheapest, 61st most developed)
6.) Argentina (56th cheapest, 46th most developed)
7.) Colombia (20th cheapest, 83rd most developed)
8.) Romania (59th cheapest, 49th most developed)
9.) Poland (75th cheapest, 35th most developed)
10.) Sri Lanka (42nd cheapest, 72nd most developed)
© Peter Wade