I certainly haven't and I would expect to get slapped with a fee by Australia Post if I did so. The limit is 2cm.

The issue with couriers is twofold -

Being home for collection.

The buyer being home for delivery.

It's not like Australia Post where the buyer doesn't have to go far to collect a carded item. Couriers generally have few pickup points available. I would be loathe to inconvenience a buyer (especially without asking first) by saving a buck or two using a courier then them having to spend an hour and tewn bucks in petrol just to accept delivery. A good way to get a neg, imo.