How often do you manage to stay within your budget? Your stated expenses for accommodation, travel and food already add up to $9,500. That only leaves $500 or so for utilities such as electricity, gas, water, broadband and TV as well as other things such as your mobile phone.
I was speaking on the phone last night with a long time local friend, and in areas around Yuen Long and Tuen Mun you can still find moderately small sized flats to rent for 3-4k per month. Granted that it'll be buses only and not near MTR stations, and very local.