The main problem with your question is that its impossible to answer. If you come to HK with a large international bank, you might expect a housing allowance of up to HKD100,000 per month. Our company brings in expats that want to join us in HK, we have zero housing allowance.
And everything in-between.
As others have suggested, the cost of accommodation varies enormously across HK. The usual trade-off is travel time vs cost vs space. You can have one, not all three.