What is the cost to change a tourist visa to a Non-Immigrant visa in Thailand?

Thank you Tod.

You can apply to convert your 60 day tourist visa into a 90 day Non-Immigrant Type O visa based on being over 50 (retirement) at most immigration offices for 2000baht.

You need to meet the financial requirement of 800K baht banked in a thai bank account in your name OR a notarized affidavit of income from your consulate stating you get 65K baht a month in income OR a combination of the two that equals 800K baht in a year.

Some offices can't do it, which is probably why they're telling you to go to the thai consulate in Penang to get a 90 day single entry Non-O visa and then apply for the yearly extension of stay once you come back into thailand.

I would go back and ask the immigration office if you can do the conversion in-country BUT not use the words "retirement visa" because there is no such animal. Ask them if you can apply for a 90 day Non-O visa instead.