I recently came across someone doing these. I thought what a great idea for us serial renovators or the home upgrader. Just get a crane to dump granny flat in front or back of house, and generate an income whilst renovating - and have property available for rent so get tax deductions.
And for the home upgrader - not having to leave the site for the 6-12months it takes (and worse still have to move in with the family).
I am thinking why not capitalise on the new NSW changes.
Anyhow the granny flats, are 40-50m2 2 br bath and kit nicely done, they are storage shells which have been rendered with french doors and they look great - the guy is making them in Melb and had some experience with the mining accomodation market. From memory about $60k?
Let me know if this is what you are talking about - and I can try to find the info.
Hope this helps
Jane