I too have had great success on Ebay buying used gear.
AU prices *are* crazy - when I see ads here on APUG for free 5x4 enlargers and some of the gear on Craiglist US that is mentioned makes we weep!!!
I picked up my entire EOS film system compliments of Ebay - there is no way I could have done so in AU. A used EOS1 body (Mk1 I think) set me back $195 including postage, the same in AU at the time - starting around $695, if I could find one, and that would have been a *really well used* one.
I've been stung once; my own fault as the original seller of the lens sent me an email regarding the second seller's claims. I brushed them aside, believing I could have the AF repaired by Canon - alas, not to be, as the parts were no longer available. Ended up selling it on Ebay myself, with full disclosure of AF problem, and the sale left me $100 out of pocket. Lesson learned - if it sounds too good to be true, it usually is!
I admit do prefer to deal with 100% feedbacks, but sometimes that isn't always possible. In which case, I use the feedbacks as a gauge - check the negatives and if I feel ok with them, I'll buy - I don't consider postage cost and import duty "gripes" per se as valid negatives, these things are clearly obvious, as are returns OS that require you to pay for the postage back.