When it comes to South America and affordability, I'd look to either Ecuador or Colombia. We recommend Uruguay as well, but things (while still costing less than in the US, are more expensive than in those first two options).
Cuenca, Ecuador and Cotacachi, Ecuador are excellent options
https://internationalliving.com/countries/ecuador/cuenca/
https://internationalliving.com/countries/ecuador/cotacachi-ecuador/
Medellin, Colombia and Pereira, Colombia are excellent options as well
https://internationalliving.com/countries/colombia/medellin/
https://internationalliving.com/countries/colombia/pereira-colombia/
And, too, I'll simply say that smaller communities in Mexico can be very affordable as well. You might consider, for instance, the Lake Chapala area (that's over near Guadalajara), Queretaro (in the colonial highlands) or the northern Baja like Ensenada (that's just south of San Diego).
https://internationalliving.com/countries/mexico/lake-chapala-mexico/
https://internationalliving.com/countries/mexico/queretaro-mexico/
https://magazine.internationalliving.com/internationalliving/library/item/may_2023/4094025/