sorry i do not have the link
took me ages to find before when i needed it
but make sure you check the ground water quality
as it sounds like you will need a well how much have you been told the 2 rai of land is?
do you have the chanote number to check the plot on https://landsmaps.dol.go.th/
even in more expensive parts of korat, farmland shouldn't be more than about 350k/rai if outside the village
make sure you get chanote checked out as other have mentioned some are zoned for agriculture only or cannot be sold (yet)
i am in Korat, i paid last year, 2.8m for 7 rai on 4 plots, in the village, have main road access, power, water etc.
also do not forget your land may need to be raised before it is ready to build on this can be expensive and take time.