While popular in the USA, Australians are certainly getting in on the act. Fred's Tiny Houses, based in Victoria, build trailer-mounted homes for as little as $50,000 - less than the cost of some car spaces!
The Tiny House Company (Brisbane) also construct 'tiny homes on wheels' suited to your needs, like this a timber framed house built on a heavy duty trailer. "It is a fully functioning home with a modular deck that attaches to the side, a remote controlled retractable bed that converts the living room to a bedroom, and a multi-use main space." Genius!