Try this website to get an idea of rental prices.
https://www.squarefoot.com.hk/rent/
If you have not already been to visit HK as part of your application process, then you really should do so before accepting an offer.
You know, how there are certain times in your life when you remember exactly where you were when something major happened? Like 9/11. Like the Tsunami. Like Hiroshima (OK, ... I'm not that old). Well, ... the first time you see a HK 1000 sqft 4 bedroom flat is like that.
Be aware that ...... "a 4bd apartment not crazy expensive" and your other requirements are mutually exclusive. Do your research. Good luck.