Interesting reading, Xausa. Just to be clear, the price asked for the Briley choke tubes is from the Merkel factory($786). The Australian importer, Granite Arms, is merely passing on the price(in fact, this is a discounted price!). Garnet, of Granite Arms, has been wonderfully helpful, as has the dealer I'm going through, Pine River Lock and Gun. I would recommend these to anyone.
The Miall's price includes the threading and the tubes.