I have just found out about this thai goverment web site where you can find full set of detailed drawings. Here is the link
Sorry, but I don't know how to make this link active by clicking it, so you will have to copy and paste the address in your browser.
You will find 33 different models, ranging from 20 s.m. to more than 1,000 s.m. This web site was already mentioned 2 years ago by CTH member Andy but I thought it would be a good idea to re-post it. The web site is in thai language but with a bit of patience you will find your way through. Alterantively check out this other web site, in english, which contains the same models and their blueprints:
Check out models 27 to 30 which I think are very nice and in a true thai style.
All those blueprints can also be obtained from your local Ampur.
Attached to the models are also an estimate of the costs. However those estimates are 4 years old and therefore need to be used with great care. I think you should be able to find in the local Ampur somebody able to give a feeling on the escalation of those estimates.
They are yours...