I’m a hoarder of cardboard book boxes and cereal boxes. I try and keep the larger ones so I can it them to support my books. Postage -look up Auspost and get a quote if you know the weight and dimensions etc. They have a calculator to get an idea.

Make sure you have a business account with Aussie post. The more you send the more you end up saving - you move up their tiers and get discounts. Also as pretty as your own packaging is, I’m going to be using Aussie post parcel bags because then you get the flat rate if the weight is correct