Qld just got Costco.. In next suburb from where I live, so not too difficult to visit.

DH and I ventured there tonight and found a few things that suit our day to day shopping. But I have wondered, do they always stock the same goods? So I can know, within reason, that if I need something I have bought in the past, I am likely to still be able to get that item again? Or are they like Aldi where they change stock lines regularly?