The most cheap international school (Seoul)

Hello, we are planning to move to Seuol and I worry a little theme schools for expatriate children, because we have two kids,
1. Can expat children study in private schools Koreans?
2. I was looking at international schools and they seem very expensive, there are more economical options? where I can locate most economical international schools? ($ 12,000 – $ 15,000)
In advance, think you very much for your advice
Best regards,