I live in Bangkapi area and have a 4-bedroom, 2-bath house that it runs me 7000 baht a month and it's very comfortable. I know of several places in the area, and it's a middle class area, quite sufficient other than the traffic on Ladprao, and the apartments run 4500-8000 with the norm being 6000. I had a studio apartment that I used as an office, brand new furniture, clean and quiet, and it cost me 6000 a month plus another 2000 for electric and water.

So you can live off 30k but you're not going to have many extras.