All the best with you plans P-son, not sure if the following link helps or not, as its not about building a house, but i found it interesting to see house prices in Issan.
FBI Udon Real Estate, Udon Thani, Thailand.
I particularly liked this one, for the price of a garage in the UK
FBI Udon Real Estate, Udon Thani, Thailand.
OK so quite an expensive garage then.
good luck amigo