What are the 3 money values in MoneyCollection for?
supplierCost is the price that the supplier is charging - i.e. the cost that premierInn charge to stay at a hotel (in the suppliers currency)
billingCost is the price that the user will be billed in, currently always in GBP (converted from the supplierCost)
preferredCost is the supplierCost converted into the users preferred currency