I did it a while back, it was under 1000 thb for 2nd class ac. Took abt 12 hours.

When I took the sleeper train down to Surat Thani, I paid extra and hired a compartment of my own. Quite difficult to sleep but worth the experience. If you need any more details, just let me know. In terms of price, I think it was even more expensive than a flight (certainly heading towards 2,000 baht). Hope that helps.

Thank you both Yes, the private cabin, I would like to know more. How is it? What things are inside, like comfort?

@adeline It was quite a comfy little space (air-conditioned). There was a bunkbed and a basin, with a shared toilet and shower nearby. In terms of the journey itself, there quite a few jolts and rough braking throughout the night, but that seems to be fairly standard.

Thank you very much! This is very useful information for me.

I did the trip myself many moons ago. I also had one of those private rooms. Word of warning: the electricity socket for charging your phone, etc. is way up by the ceiling 🤔 , so bring an extension cord, or your phone will be dangling by its lead all night!

@lars This is a very good tip. Thank you!