I know a guy who is working here illegally and who has been doing the visa run for about 3 years now. You could certainly manage it a few times, but it depends how long you want to stay here. However you won't get an ID card, you won't be eligible for any local services (i.e. medical treatment) and your time here won't count towards PR if that's what you want.
Owning a flat and having an old ID card doesn't make a difference, either you find an employer to sponsor you, find a local who'll marry you or risk doing the visa run until someone gets suspicious.