One thing I'll mention for US citizens. Aetna's Mobile Healthcare Plan seems fairly reasonable. I'm paying around $300 a month total for coverage for my partner and me (most comprehensive coverage, highest deductible). Apparently it's still valid in the US so long as you spend the simple majority of your time outside of the US (i.e. 6 months abroad).
https://www.aetnainternational.com/en/individuals/health-pla...