What are the financial requirements for a retirement visa or Non-O visa in Thailand if I want to live in Korat?

Hello, I want to retire in Thailand in the korat area at the end of this year, looking at the financial requirements for a retirement visa or I believe the other option is a non o visa for a year and then extend it for another year and in that time deposit 65,000 or more into a Thai bank account, would this work or do I have to stump up the 800,000 , no intention of getting married at the moment, have friends in Korat who have married and built their own houses, love the area and the friendly people

I don’t know whether to go and use an agent to simplify the process and I’m not sure if this is hundred percent legal, is there any comeback on using an agent, Thai government websites say that if you can prove from your pension provider that you have over 65,000 baht per month paid into a Thai bank account then this negate the need for the 800,000, I’m not sure what to believe because my friends are telling me that no bank or pension provider in the UK will certify this, confused