I would not have though that an eBay price, for an item that is not widely available here, is a very reliable indicator of anything. That being said, retail prices in Australia do often seem scandalously high for a lot of stuff - especially photographic equipment.
The good news is, we can escape the mark-up by buying online from overseas. So I get all my film and most other photo gear from the US.
Alternatively, on those rare occasions when the UK has something at a sensible price, I can order from there. The Australian GST-free threshold for imported purchases is AU$1000. So if I buy something from, say, Silverprint in London, I don't pay the 20% UK VAT, and the cost of shipping to Australia is often less than the UK VAT saved. If the order value is less than $1000, I don't pay any tax at this end either. The result is that I can generally get goods from the UK sent to my door in Australia more cheaply than a Brit can buy them on the street there himself. Strange but true.