Can you really buy Collette Dinnigan at the op shop? The Salvation Army store in St Kilda seems to think so (cnr Inkerman Street and St Kilda Road).
You do occasionally come across luxury labels in the op shop - they're usually a bit obscure though. I've certainly never seen Prada or Gucci but have come across Yves St Laurent, Marni, Polo. The most luxe item I've ever bought is a men's Romeo Gigli jacket. Perhaps they have these special designer sales on a regular basis because at the time when I enquired about the price ($50 - whoa) the staff member said something to the effect that it was left over from the designer sale. I'm glad that I didn't buy it at the sale (for $50) as he sold it to me for $15. What's your swishest op shop purchase?
Anyway, I'm not counting on there being any bargains this Friday but I will be there at 8:59am.