I am not an op shop person generally, but I felt like going to one today. Reddit told me the best area for op shopping is Elsternwick with 5 op shops and 1 bric a brac shop. Unfortunately none had what I really wanted - old train books, mags, newsletters, etc (the Vinnie's in Bacchus did and I bought heaps of them a few months ago), but I bought a few things anyway. I go to op shops mainly for finding cool stuff I can't really find anywhere else, not so much the prices. I got a coin bank type thing that looks like a royal mail post box from the UK (at least I think it's meant to be a money tin), a few books, and a set of 3 photos of paris on canvas frame things for 12 bucks.