Julien Peltier you'll need to go to Perth, Australia or France to get a METV if you carry a French passport, as Robert Lagas explained above

1. You won't need kip. Use baht and you can take your change in kip. But every place you go will accept baht, including taxis or small shops etc.

2. The flight is dirt cheap. There are several airlines offering it for what you pay for a bus ticket plus a meal. And you don't spend endless hours on a bus.

My answer would be that the few dollars (or € £ ¥ or whatever) you might possibly save on a border run is outweighed by the easy and convince of not having to bounce over the border and go through the hassle. Other may have a different opinion. An extension is 1900 baht. Only you and your husband would have to do one. I could be wrong about your 16yo. But your younger ones are exempt from any punishment even though they overstay, so many times immigration doesn't even bother processing extensions and just had the parents stay current. (This is what I've read, I don't have kids so no first hand experience, just something to think about).

If you get a 60 day tourist visa from any Thai consulate or embassy you can extend that within the country for another 30 days, giving you 90 days in Thailand without having to leave the country for a new visa or stamp. Your end of november departure date would determine if it falls within that window, but it's highly likely and only a day or two over if you do leave the last day of november (not doing the math just glancing at the calendar).

Details like this are useful. Hopefully we'll hear more reports, so we can get a clearer picture. But it looks like someone told immigration to start enforcing this. These are the details that can help other travelers avoid the same pitfalls.

I travel internationally somewhat regularly, and I usually don't bother carrying cash because this was never enforced in the past. You may have saved many people the same headache you're experiencing by sharing. Thank you. Good luck getting back!

This is helpful for many

Please do not do that!

Where were you denied entry? Suvarnabhumi? Any other details you can provide to help others avoid this in the future?

I wish I had answers for you. The above seems correct, that the visa was not cancelled and you just need to produce the funds. I'm sure someone with concrete knowledge will come in soon.

Thank you for sharing, hopefully we can learn something. I know I always should have cash. I'm on long term extensions of stay and have never been asked, most times I don't carry that kind of cash around.

I think you'll be fine as long as you don't give them a reason to ask further. There's tons of young people in Thailand traveling for long periods on a budget and that in itself is not suspicious

I've seen the 20k cash requirement enforced exactly once, for a guy in elephant pants, a singlet, and dreadlocks. I don't want to say it was the guys appearance that prompted it, but it's a high possibility seeing he was the only one asked and was the only one unpresentable in a professional environment.