It is not often that it is easy to identify the cost of the exactly same product in different stores (looking at you Mitre10 and Bunnings with price matching) but recently saw a great example between Costco and Harvey Norman -with stores almost next door to each other.
A Waterpic flosser set cost $174.00 at Costco. Therefore cost to them -wholesale cost- would be NZ$ 121.80 given the sale price is 30% above cost
Identical set (sold as separate units) is $454.00 at Harvey Norman. That means the markup is approximately $333.00 and profit margin of at least 200%.
No wonder things are expensive here. Surely size and scale would not make that much of a difference.