Let me try to clear up some misconceptions about international schools.
Fist let me say that I am one of those people who are at the lower end of the high end salaries. Why? Simply because I am a local guppy. Still, it is a very nice wage.
The oversea hires are fished from a deep hole and treated as such.
The top schools like ISB, Harrow, RIS, NIST, and BPS all tend to hire from overseas. These teachers want a salary just like they were getting back in their home country. Normally they get that and then some. I personally know teachers (not administrators) making 170 baht per month. Keep in mind this does include housing, etc. And these teachers are still not happy. Most of these teachers will only be here about 2 years before moving back home.
Back to the money. The big schools as mentioned above will all start out at least with a basic salary package of 120,000 per month. Throw in housing from 20,000-40,000 per month, along with a free airline ticket home once a year. Most teachers depending upon their home country might not have to pay taxes for the first two years while teaching in Thailand. In comparison, I pay almost B10,000 per month to the Thai government.
But this is just the basic package for many teachers. Throw in some additional responsibilities and the net income can increase dramatically.
Has been mentioned, the medium tiered international schools will offer salaries from B60,000-90,000 depending upon qualifications and needs of the particular school.
Now the administrations of these schools are a different fish all together. I have met one head guy who was only making B125,000 per month. Another had a package worth B240,000. And finally, I met a big fish who was having trouble with his half million baht per month and his living expenses both here and abroad.
Much more to this issue but perhaps you got your line baited.