Snacks. I love a UK snack called "twiglets" which sell for about 99p a large bag in the UK and cost HKD55 for the same bag here (ie 5x the price). However, I have found that someone out there has realised that there is a market for Twiglets in the Gold Coast and when they are past their sell-by date, they send them to MarketPlace in the Gold Coast, priced at HKD15 a bag, at which point I buy everyone I can see. (Done this three times so far, a few months apart!).
So - it's more about price than availability in general. Ideally you'd want to wean yourself off expensive overseas stuff and go local .... which I have for everything except Twiglets! We all have one vice