Types of car insurance in Thailand… https://www.roojai.com/en/car-insurance/compare/
unfortunately, the rest of your question cannot be answered with the information you gave. type of car, value of car, age of car, age of driver, etc. etc. is needed.
As an example, we are paying 11,000 Baht for our Everest and nearly ฿50,000 for our E350e
First insurance is a good idea as if you have an accident the rep from the insurance company who comes to the scene of the accident will deal with nearly everything for you….provided it is a reputable company