If you've just turned 50 you may be best to leave the country, get an o-a visa which requires 12 months health insurance in advance but isn't too expensive if you've only just turned 50. You need to show the equivalent of
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0 baht in your native account. You can then start sending the required monthly amount from abroad to a Thai bank account so you can then go to an O visa the next year (or even the year after, as a multi entry o-a can get you almost 2 years if you border bounce at the right time, and then you won't need to have
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0 tied up in a Thai bank account, as long as the required minimum monthly transfers have been adhered to