hi
v bought a ticket for our helper from manila to HK (one way) on cebu pacific which cost us appx. HK$ 750.
however ensure that you get a receipt from her stating that she has received the money in lieu of the air ticket to avoid any problems later on.
actually i booked for 30th dec return from manila to HK which is peak season but i booked 2 months back. however, if the helper is fine with this amount i.e. 750-800$HK then it is okay otherwise worthwhile checking with a travel agent.