Try to negotiate a transportation allowance, which will be about 1000 QR/m or a car that you can share with another teacher.

Also try to negotiate full medical coverage.

If you don't drink and smoke your monthly expenses for groceries and outings could be around 3000 to 4000 QR. For a couple 5000 QR/m is ample, again assuming that beer is not the main ingredient of your diet :D

If the offer is reasonable or not; it should be more or less equal to what you would be earning in your country of origin, before taxes.