I don't think your 12-year-old son will to go school by bus! You will see the situation by yourself when you will be here. So your spouse needs one car. Children can play freely only inside walled/fenced gated community. That means you need to rent an apartment/villa inside compund....Normally there are pool/gym and service, and rental is more expensive than single apartment. Check the website of american/international school, then you will have an idea of tuition....COSTS!! If your target is to have your son play safely with other kids, then the only way is gated community!

Put all together, if you have to pay rent and school and to keep the life decent, 21K is far from enough. Forget about saving something from 21K..