Do I need to have money in a Thai bank for a Non-O visa after entering Thailand on a VOA?

I don’t think you will enter Thailand on VOA but on a visa-exempt for 30 days.

Generally, you just need your funds in your Thai bank account, no need to be seasoned, when you apply for an in-country Non-O visa. But a few provinces require you to have your funds seasoned. You need to check the province you are going to settle into.

It depends on how quickly you will sort your things out in Thailand if SETV would help or not. Some can manage everything (open a bank account, find and make a contract for long-term accommodation, etc) within 30 days, no problem.

FYI: SETV gives you some benefits than visa-exempt entry such as,

- less hassle with the airline upon your check-in (you may be asked for an onward flight ticket within 30 days by the airline for visa-exempt entry)

- 60 days on entry (30 days for visa-exempt)

- up to 90 days with tourism extension if you need time (60 days total for visa-exempt)

- SETV fee at the Thai embassy is cheaper than the extension fee at the local immigration office for up to 60 days stay