I once sold a Meade LX200 10" SCT with mount, wedge etc. It was a big rig. The buyer was in Karatha by memory, and I was in Sydney. We couldn't really have been further apart lol. It was quite a big thing for me to package it all up, purchase a shipping crate and have it delivered to me, get all of the cartons packed safely into the crate, pad out all of the dead space, find a reputable shipper to get it to the other side of Australia and organise the pickup (forklift load only). I know that this is probably as extreme as it gets with this sort of gear, but I can understand why some sellers may not want to get involved with packaging things ultra carefully for interstate shipping. It can be a bit of a job depending upon the item of course. I do see some sellers noting that an item is too heavy to ship when it actually breaks down into cartons under 10-15kg a pop though. I guess that it can get down to the seller's physical abilities too. When I sold my Obsession 15" it was a definite pickup only affair
But, say, my old AZ-EQ5 - I would have shipped that Australia wide.