If you are up to wrenching (as the yanks say) then your best investment will be an Audi parts book for your model in one form or another. From that you can input the part number directly into your search engine and get some indications of source. Many seals etc are just brand name parts and you can order them from any bearing supplier. Inputting an Audi part number can also throw up a number of Australian suppliers that you may not know of. There are a ton of US based suppliers, UK and Euro too. My recent experience is that I've purchased locally cheaper to my door than from any OS supplier, but only on some parts.
If you do purchase from OS, just be aware that some parts are for LHD cars and some countries do not get our models so some parts will be similar but not the same and may not work.
C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : modified -- B5 Audi 1.8 quattro 132 Kw -- 2007 VW Touareg TDI 3.0 with air suspension and lockers-- UNIMOG 404 TLF8