OP still didn't confirm if he is Thai or not. I'm guessing he's Thai, because he said that he's going to be buying the land & as we all know, foreigners can't own land.
I don't get why the OP, being Thai, didn't ask his question on a Thai forum rather than asking a bunch of non-Thai people on this forum. Surely a Thai forum with Thais who know Thai law and have experience carrying large sums of cash for property deals would've been better imo.