I just buy a cebu pacific airline ticket for my maid, only HK$890+HK$387(tax). If you buy the oneway ticket maybe can cheaper. Hope this can help u. You also can check cebupacificair.com.hk
I just bought one cebu pacific airline ticket for next week- single ticket, just $857 (included tax & fuel surcharge). If you want to know the agent, I can give you the email or tel.
Yes, open ticket is much expensive. As my agent told me that if you not buy an open ticket, you will bear the risk for the maid to claim another ticket if she can not go back within 2 weeks.