For that money you could get a converted Commuter van, Coaster or a Mazda 3500 in pretty good order. SE Qld is probably the best area to look for one as well.
EDIT just had a quick look for motorhomes 20 to 30K and this was the first one:
I havent done any travelling yet but the time has come that for my health I want to get going.
My parents have been travelling for years and they love it. I will be solo with my dog but I see there are other solo women out there :)
I need to get something reliable its a big step to buy something hoping you will like the travelling but I am feeling positive.
I have had 2 friends struck down with cancer in the last month I am getting itchy feet you dont know whats around the corner hey?