I am married to Thai so only 400k for 2 months. Yes I agree if you can show monthly income better. I prefer yearly as less to worry about and when you do it once it gets easier. We always make extra copies and just reuse for the next year. Always in and out in about an hour or so.
I am from Toronto and at first did the 3 month visa from Canada but did not have all paperwork done so did a 2 month extension in Thailand and then left to Singapore then got another 3 month. Since then I just keep renewing my yearly visa. If you don't want to keep the money in the bank you can use the 3 month visa and in Thailand extend for 2 months without leaving. So if you intend to go back and forth this method would enable you not to have to leave Thailand for 5 months at a time. If you have the money in Thailand just do the yearly and you can come.and go back and forth with yearly renewals