As to OP, budget $20K for your flat and you can stay either on HK Island or Kowloon near ICC like Olympic, in a 1 bed or studio in building near MTR with facilities.
I don't know what locust is on but you can definitely get a flat for under 20k in HK island. Just need to search a bit. I had a flat with two bedrooms in Kennedy town for 12k when the station was opened.
You said ICC, is that Natixis then?
My friend lives in Kennedy Town, 2 small bedroom apartment and only pays 12K, nothing fancy but still beats paying 20K for a single person.
I moved here on my own as well OP and have had no issues (female as well). HK is one of the safest places I have ever lived in. You still need to be smart, but I have had no issues and have walked home more than once in the early hours of the morning.
You can certainly get a flat for around 15k on the island in the areas you are looking for. Yes, they would be a bit older and have no facilities, but a lot of the times they are renovated and look very nice inside. Just take your time and have a look at a few. Be firm with your budget when speaking to the agents. If you say 20k, they will only show you apartments in the 19-25k range.
Good luck! You will really enjoy HK!
To tell you the truth, my manager had told me repeatedly NOT TO bother helping those who were seeking rentals with a budget less than HKD$15k/month. He said it was not worth it, because, first of all, there are very few options available even within the vast area (I could do a search on the company database and saw he was telling the truth), and the few available options are pretty bad anyway so my clientele (a majority of which is western people) won't like them so the success rate for me closing a deal would be low...
And that was about ten years ago, Hong Kong's rental market has soared since.
I am just being realistic.