I can get anything in the Meguiar's range, except:
Those that aren't sold in the US (there are actually some things produced especially for the Australian market, such as the lambswool mitt and green microfibre glass cloth); and
Those that would be classed as dangerous goods and can't be flown to Australia. That rules out aerosols and cleaners marked as corrosive.
Items which are relatively low in price, but heavy, are best purchased in Australia (if sold here). That includes car wash liquids, most window cleaners and bulk detailing . Even if the US sold such low-priced items for 40-50% less, the cost of shipment would mean that you'd pay less from a local shop.
Items which are small but pricey are best purchased from the US, including waxes, rubbing compounds, specialist cleaners and especially cleaning accessories (e.g. microfibre towels).
So yes, I can get the liquids in the tan coloured bottles. But I'd get the big detailing bottles locally - when there isn't a sale, Repco offers 10% off to NRMA members (that's if they sell it).