MelbourneIT are ripoff merchants, They charge premium prices for what everyone else can have anywhere else at a fraction of the price. Probably part of the reason they just purchased TPP / Netregistry
If memory serves me correctly, they were the first .au domain registrar and continue to offer over inflated prices to dickheads who would actually pay what they are asking.
Crazy Domains charge a fair bit more than some others, but I've used them a lot and have had no issues.
Unsure about .com.au to be honest but if you sell a .com normally a 60 day restriction applies, now i know godaddy enforce this rule but i am unsure whether it is a icann rule or a godaddy thing ? Others here may expand, many people just do a inhouse push to the person in the same registrar when there is a 60 day restriction. It is not unusual for domainer to have multiple accounts at different registrars for this purpose. (inhouse transfers) they may transfer out to their favourite registrar later on after the name is in their account
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There have been comments here about .com.au's being caught and then put on the aftermarket the next day ???