I think there are a few things that you might not find, or at least I had trouble finding a store stocked any of the following:
Aspirin 300mg (headache strength)
Nurofen - 48 and 96 tablet packs = not available?
Nurofen Plus - not available
Panadeine 15 - not available
Panadeine (regular) - not available?
Over the counter sleeping tablets - Restavit, Dozile, Unisom, others?
With nurofen, I was only sold the smallest packet which works out very expensive. (when comparing the per-tablet cost to that of larger packs)
This is probably what your friend was referring to when he mentioned cost, as you can't find bulk packs for many things.