Army disposal stores where you could actually buy old military equipment.
Record stores. Spend the hole day in the city going from 1 store to the next. Start at central and zig zag George, Pitt, Elizabeth streets various record stores working your way up to towards Centrepoint, from memory there was a big record store bottom of the Strand Arcade. Find Redeye and in the early days Utopia was Martin Place. Exhausted by the end of the day and go home with a few goodies. Late 80's. early 90's weren't so many boutique yuppy shops back then in the city so plenty of interesting shops in town.
Use to be a massive shop on Parramatta Road Leichhardt too spend a couple of hours in their and wouldn't even make a dint. Just a filthy shop full of records probably not long after CDs started to take hold so abudents of records those days.