My sister-in-law is looking at retiring from her store business she has owned for 30 years in Chiang Rai and wants to fix up a vacant house she has. Plus she just bought extra farmland to potentially build several new cottages on, keeping a lot of the gardens there now. She wants to design, build and rent to foreigners. I have only visited once but I believe she is near the old airport area. Any idea what kind of rents she could get from foreigners?

Post in Chiang RAi forum for better response. Look at what estate agents in the area are advertising.. One is called Lanna Realty the other new one on the block with plenty of properties to rent is Kay estate agents(google). There is a shortage (in my opinion) of good quality houses around 12 to 15000 baht, this will be your main audience of foreigners.