Hi Don,
Consider joining the NSW mustang owners club, a lot of the good cars are traded within the club to other club members, and are not advertised publicly.
Click on the two black mustangs at top of page to go to the Owners club.
I would stay away from cheap convertibles, without having an expert inspection.
Also consider reaching out to Big Als mustangs, he may also be able to help you out, his link is to the right of this page.
Cheers
Keith