I had major (non life threatening) surgery on Koh Samui. Before we left the US, I had been quoted $35,000 for just the surgery (not anesthesia, room, etc). Insurance wouldn't cover, so I had it done here in Thailand.
I found a good recommended surgeon first, and he gave me an option to have it done at an international hospital (200k baht) or govt hospital (100k baht/$2857 usd).
I chose the govt hospital with a private room instead of patient ward, and it was great!
This price included everything. All in! No extras of follow up.
Will your child be going to school in Thailand? If so, ask the school they will be attending what's involved. Normally, the school handles the paperwork. Good luck!
Seriously, you will get different answers at different banks AND it can differ with location too!
We were told we had to have a bank account to get retirement visa, but told by the bank that we had to have retirement visa first. It was a very frustrating catch 22.
If you go to a bank in a high tourist area, your chances are better.
Please be aware that if you don't have an IDP or Thai license, your health insurance will NOT cover you if in an accident. It will also not cover if you're not wearing a helmet or have been drinking. This is info that every tourist should know.