eBay Freight Charge unbelievably cheap!!

[GlennSprigg]

The 'missus' and I regularly purchase things online, and often from overseas too. However, recently we have
purchased 3 items, from within Australia, at different times from different suppliers over the last 2 weeks...
They ranged from $86, $120, and $70, and were about 15kg, 30kg & 10kg in weight. ZERO freight cost???
They were all from Melbourne, to our remote town out of Perth, which is about 3,500 kms. Received in 7 days. 
I really don't see how they can do it!, or if they are stuffing something up with their paperwork.

P.S.  They were all about 1/2 price from ordering/buying locally...