Come to Thailand and do it yourself cost for retirement visa is 3900thb in total after that you pay 1900 every year but you will need a bank account and
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0thb for the information for the immigration office to see every year or
It's much easier for you to come to Thailand and once you are here then apply for the visa and you don't need to worry about the insurance, also you can find a insurance company that suits you once you are in Thailand. But I can tell you that it's not cheap for health insurance
So sorry but it's not going to happen your over 50 now and having not been working in Thailand for the last 10 years or even paid taxes in Thailand you can forget about it