Depending on what country you are from, if you need Covid coverage just to satisfy Thailand requirements, you should check the online quotation form for the Thai government arranged insurance from Thailand General Insurance Association. For example, if coming from Hong Kong, cost is only one third of Luma's cost for one year policy, and less than half Luma's cost for 90 day policies. But it isn't general health insurance, only for Covid. From the UK, the rate is higher than Luma so it depends where you are from.
***********************