I don't know any specific prices, but if you buy > $300 in one tax invoice in Aus within 30 days of leaving the country, you can claim the GST back at the airport. Works out about 9% or so. You need to have the bag & receipt with you after you check in.
With the excellent dollar value right now, Prada retail prices in Aus are approximately US retail price + GST.
Example, the applique lambskin clutches are $895 US retail (taxes added at checkout for US residents) and AU price is $990 (includes GST). Not too shabby.
Finally a brand that aligns its prices according to the exchange rates!
Im pretty sure thats lower retail prices than Singapore.
Claim GST back at the airport and i believe you have yourself a better deal.