The retail value of an item is the price the buyer paid for the goods. Retail values often reflect the market value of the item (ie. MSRP.)
When creating a shipment, you should always be indicating the retail value of the item(s).
Retail value does not mean wholesale where bulk discounts may be taken into account. Also not accepted as retail value is the material cost of the item.
Please note: Shipments cannot exceed USD $800 in retail value when sent to the U.S. or other international destinations. The maximum retail value for Canadian shipments is CAD $2500.