Just to give one more point of view.......As of January, our helper will be in that range. We hired her at the minimum and increased her wages pretty substantially last January and will do so again this year (and next year etc). When we hired her, she had been out of HK for a while to take care of family in the Philippines so (my guess is) she didn't feel she was in a position to ask for more than the minimum, even though she has loads of experience/skills.
Initially, it was my husband who suggested the large increase (our helper didn't request it) and I was wary because I thought it might set a precedent that we would feel compelled to stick to. We talked it through and decided that even if it did, the value that our helper provides to us still far and away exceeds what we pay her. We continue to feel that the higher pay could be really meaningful to her and her family and is not going to break the bank for us. In our home country only the truly wealthy (i.e., not doctors, lawyers, mid-level bankers and the like) have live-in help, so that probably makes us appreciate her all the more.
To cut a long story short, whenever it is we leave HK, our helper will be back in the market and I would think that she would at least tell potential employers what she is making and hope they can match it. So, if helpers quote you those figures, they are not necessarily being greedy or unreasonable. That said, just like when any of us moves jobs (particularly when we are forced to), the opening salary request may be just that and the helpers you are talking to may be willing to accept less if they feel they can't find the right situation otherwise.