My hubby and I are applying the independent skilled migration through an agent. The fee they charged are about HKD26000.
I think, whether it is expensive or not depends on how complicated of your application. For my case, because we applied in "family" base, it's relatively complicated then an idividual. My friend also applied through an agent. But becuase she is an individual, she only needed to pay ~$1XXXX.
And, I don't know which oppucation you belongs to. For my hubby, he needed the assessment in Oz authority to prove his professionalism and transfer the recognition from HK to Oz. So if we don't go through an agent, we are afraid we don't know how to get this proof.
Moreover, the migration policy changes every six month. The next change date is believed on 17 Nov 08. For better control of the successfulness of the application (say, to lodge the application before the changing policy deadline in order to retain sufficient marks), an agent may provide you better arrangement.
Yet, all I have said doesn't mean that you must approach an agent. But I would like to list out the notice points to you. I also think that the service fee I paid is a little bit expensive, particularly because we have sufficient marks and can straightly lodge the application. In the eye of the agent, we should be a simple case.
P.S. One more thing: I think the price may not be the most important. But the most important is to choose a reliable agent who is capable in following through your application and make your application success.