We manufacture tampers to any size, including for the Brevilles. 52mm will be too large for the Breville, if youre just after an approximate fit youd be best off hunting down a 51mm or smaller unit. Otherwise wed be happy to help out with one that fits properly.
It does depend on your budget though - a Deluxe will set you back around $130 including postage, though as some of the comments on the other thread you started http://coffeesnobs.com.au/YaBB.pl?num=1266020024/ show, people who have them feel theyre worth the money.
Though I guess if youve started this thread perhaps youve already decided to try an off-the-shelf one?
Greg and Robin