I heard about "The Shiralee"on 2SM talkback radio and thought it was a great alternative to the granny flat. The Shiralee is made by Street Swags an Aussie non-profit org that provides social housing for families and people living it rough on the streets. You could add $200+ per week to your rental cash flow with a 2 bedroom base unit at $10K, or double the price and get the veranda, VJ lining, electrical pack, kitchen, guttering, colonial pack. Cost $9K (1 bedroom), $10K (2bedroom) or $14.4K (3 bedroom). Someone on Centrelink benefits could payoff the 2 or 3 bedder in 5 years. Like a caravan, it's movable so technically you don't need council permission to put in (check with your local council though). It comes with a ready to use kit to submit to council including certified engineering plans if required Check their website www.streetswags.org and price sheet for the full specs.