I put my R33 GTS-t up for sale Sunday just gone as a sorta semi-serious sale (all sorta depends on what happens over the next 2-3wks with work, more so who im working for).
Carsales = $10/unlimited and has got me 2,759 views of my small ad (ie the list of all R33 GTS-t cars) and 72 views of my large ad (ie all my pics/car specs/contact details) with no phone calls.
SAU = $n/a/unlimited (if it sells on SAU i'll most certainly donate some $$$) and has got me about ~85 views and 1 phone call.
I've bought my last 2 cars from CarSales.com.au and sold 1 too. Nice site, I like it.
Edit: I'd put my car on consignment however it's my daily driver. I haven't put a for sale sign on the car, waiting till im a bit more serious about it first.