Have you done anything about applying to schools yet? I agree with Sgilli, please make sure you know exactly where you stand as far a schooling and housing allowance goes. You may be able to barter a bit. I know someone who recently got their place for 20K less than advertised but I don't think you could knock much more than that out.

As a rough guide, we have a Prado and a Rav4 and pay around 4500AED a month in car payments. We're buying, not leasing.