contact local rally car clubs, cant remember if some are listed on rally.com.au else cams.com.au. Ask what sort of events they run and join one. Over here in perth, you can join one club and enter the events of most of the other clubs anyway. buy a cheap car; old datto, gemini, old civic, aE82 corolla, something along those lines and buy some second hand rims and rally tyres ~$200 and your away. Level 2 Speed cams lisc will suffice for motorkhana, khanacross, autocross and hill climb events at the club level of the sport.

I've done this sort of level event for the last 3years or so, hopefully stepping it up now that we have a Liberty for our gravel play toy