Toluca, Mexico. It's extremely cheap, cool/temperate all year, and some of the suburbs (e.g. Metepec) are quite safe. Reasonable proximity to the US (geographically, temporally, and to some extent culturally) would make it a practical option for Americans. It's a profoundly "not hip" city, but as someone who just wants to be left alone in my apartment all day, I consider that a plus. The main downsides are extremely high elevation and sub-par internet speeds (likely requiring some careful apartment hunting).