you could find yourself a floor on a village house (700 sq Ft and usually 3 bedrooms - if you get a ground or top floor flat you will get extra space either from extra garden space or a whole roof to yourself) for a decent price as long as you are prepared to live out in the styx. I am pretty sure Boris mentioned in another post that he pays 6K p.m out in Ting Kok Road.
It's not so inconvenient as it first sounds as there are express buses into the Island that can speed up travel time (and in fact are sometimes quicker than the train).