hey I am a Singaporean going to HK too. I will be there for 3 years and have been looking around to a place to stay.
Try this website:
www.centanet.com.hk
they even have an interactive map where you can use to check out the place you want to stay.
With your budget and depending on the living standard which you are expecting, a good choice might be in the New Ter. or in some of the newer estates.
Lam Tin is in HK and with the MTR, you can get to Quarry Bay in 10 mins. So not a bad choice.
Well, the location of your place also depends on where you are working and where facilities you are looking for.
For me, it has to have a gym or a gym nearby and a MTR or KCR nearby. Thus Shatin and Tseun Wan are pretty convient areas in New Ter.
On Hk island side, I know rent in Causeway bay is cheaper than Mid level. Try sharing if you are going to stay at mid level.
the problem is there that are no proper gyms like fitness first in the suburban areas... argh... unless you find a place with a gym in it.
For me living in Singapore and Sydney made me accustomed to bigger living area. So I rather look for a place in the sub urban area and enjoy the scenary and the bigger space.
Some places in the outskirts have excellent hiking trails.
Hey been to a forum where someone is saying that he lives in Sai kung... It is a lovely place but i think it is really far from the city.
There are also considerations like hanging out with friends after work cos if you live far away, it might be difficult to hang out for after work drinks.
Like I said, too many considerations, which is why I am staying at a service apartment for one month while flat searching.
oh and gohome.com.hk do have good housing options and housing review where they review each estate.
so with a combination of both centanet and gohome, you should be able to figure out the place which you are staying.
another consideration is of course safety. I reckon Singapore is in a way safer than Hk depending on the area.