You can see from many posts people apply in countries that they are just visiting. Several countries nearby Thailand which are easy to get the DTV from.
It was posted a couple of weeks ago, there was a lot of response to it as the OP got argumentative. I have never searched for it, only replied and read comments to it.
Pattaya agents used to charge 3500-5K and Bangkok was around 2-4 x that. I heard of being asked for 25K recently to open an account in Bangkok. You got a good deal.
Someone posted they had to show they still enrolled in the course upon arrival at Bangkok airport. Muay Thai is the most popular option bogus agents use so those using it are the most likely to be questioned at borders. Best to have documentation of current course to hand.