Holy Moly ! One reason to live in CM is that almost everything is cheaper than Bkk area or places like Hua Hin, Phuket, Pattaya ...
But also, costs will always be less if one has some experience in what is involved. Even never having done a build here (Thailand) .... one can always learn by going to sites and watching and asking, and learning the prices of things like building blocks, concrete mix ( for the foundation) , and of course how deep the posts are set in your area.
I have always chosen local builders , after seeing their work elsewhere. ALSO, I buy the materials and pay for labor . Many builders do not want to do it that way... but then you had better be very sure EXACTLY what the materials and specs are !
Anyway... like LA .... experience and looking for a "reasonable price" can save a lot.
My wall (3 years ago) are strong blocks, with a very large base (kahn) with strong rebar (3 hun dtem and then 2 hun plawk lek ( the smaller squares )
labor per meter : 700 baht each section aprox 50 concrete blocks at 6 baht each.
Concrete mix for base (240 mix , if i remember: 1900 baht per cu meter
and then of course sand and concrete for the mix to put up the blocks
ok... probably too much info, as easier to let the builder do it all . BUT..... my cost all in was less than 1400 baht per meter. So, if paying for all to be done by builder, I would never go more than 2000 baht .
BTW: This is my first full concrete wall ... i had others before... and its strong and keeps unwanted critters of all types on the outside looking in 😉