I live in Bangkok, but have started buying coffee beans from Chiang RAI roasters. Also, from roasters in the south, who grow a different bean. Arabica is grown in the North and Robusta in the South. There is a large number of coffee roasters who will send beans to you for a small shipping fee. Many of these roasters also grow there own beans, so you can buy single producer coffee. Price is about 200 baht for a 250 g bag, however, I have also only paíd 200 baht for 500 g. Some coffees I have purchased recently from the following: Xanthocapa, Chiang Rai, Phu Sun, Nan; bata-me, Chiang Rai; Akha Ama