Greg Larkens replied:

Pete how long is a piece of string. I assume you are looking for an off road unit. It will need to be well built with a heavy duty suspension and preferably wheels and track to match the towing vehicle. An articulated coupling (eg Treg) is useful for very hard work. A criteria I personally think is essential, is that it be a hard floor unit. Campomatic, AussieSwag and Kimberley Campers are amongst the better ones but I doubt if you will get a secondhand one for the price you are prepared to pay.

Mick replied:

Pete

I have had a Cameron Heavey Duty Camper trailer that I converted to an off roader for 4 years. The advise on track and coupling is good and if possible match your tyres and wheels to that of your towing vehicle.
The Melbourne Treading Post seems to be a great place to find one at the right price.
The solid floor is a heafty added cost for dubious benefit. Quality and size of the tent is important especially for a family.
An old off road configuation is OK, its capabilities are the equal of most drivers and their vehicles.
We have had great service from ours and it gets to do about 10K of relitively hard dirt and rock kilometres a year.