Crazy money. If an agent gives advice and quality assured your application before submission I think a 10-12k THB is fair. I woukd also expect they off a full refund if rejected as long as you were fully honest with them
Do it yourself. Ask any questions here. If you really want an agent choose one that offers money back guarantee and then only for document checking before submission. Good luck
I reckon you are less than 1% - in fact even less on a DTV. In 30 years of business trips globally, for household name companies, I was asked at a border for a business card twice. Once in the UK as a British citizen (I could not look more British) and once in Japan :-).
They are strict with everyone. The actual immigration office in Chiang Mai are also very easy to deal with and helpful too. Only recently threads in Expat Groups praisng them. I have never seen that for any other offices.
I worked for a large Japanese company here. All the Expats kids went to NIST in Bangkok which was close to the office. Would need to check but I think fees go up to 1 Million Baht a year. The extra curricular was expensive. A Japanese colleague complained about all the birthday presents he needed to buy for parties every week. He had two daughters there and he said the parties were weekly. Almost crying into his beer lol