The days of inexpensive domestic help are long gone, and although many expatriates hire at least one maid, others have entirely foregone that option. Most domestic helpers are not Korean, but rather hail from the Philippines, Thailand and Sri Lanka. If you are interested in having a maid, either full or part time, it is wise to start looking early—notify the sponsor ahead of time. Having said that, domestic helpers are readily available.
As for wages, normally live-out domestic helpers would be about US $800 per month and live-in helpers are about US $500-$600 per month plus an annual bonus and a RT plane ticket. You can also get half-day helpers for for about US $30.