cheapest way (with luggage) to get to HKIA from Best Western Harbourview Hotel in Hong Kong?

For the cheapest way, transfer is needed. Considering that you have luggage, I suggest you take Island Line from Sai Ying Pun Station to Central Station (15min). Then walk to Pedder Street to take bus no. E11 to HKIA directly within an hour. The whole way costs 25-26HKD per person.