As I go to Macau a lot (Casinos ) it's actually better to purchase items in Macau over HK. The bigger and expensive items are priced similar to HK and most items will display two prices. So if something is $1000hkd in HK, it will show $1000hkd and underneath will show $1030mop. Even after the exchange rate on the MOP back into HKD it's nearly the same on your CC bill.

As most CC will give you double rates for overseas purchases, it's much better to buy in Macau over HK!