Hi baobeixuan,
It depends very much on what kind of maid you are going to hire.
For example:
If you get fresh maid (who is still in their home country), you have to pay agency fee, new insurance and certainly to fork out advance loan for the maid. If she doesn't work out, then you will have to send her back to agency to get a replacement. It also depends on your agreement with the agency for maid replacement,etc.
If you are getting a transfer maid from Agency (maid in SIN), you need to still pay for Agency fee and if the maid doesn't work out, then you got to send back for replacement, some agency will charge for paper work involved and replacement of maid is written in the agreement with the agency.
Conclusion: You need to pay Agency fee.
By the way, I have one Philipina maid for transfer for direct hire. No agency fee but you need to pay $10 for online transaction if she fits your family.