Some of the questions we often receive when talking to prospective clients who are considering outsourcing their order fulfillment are in regards to the shipping cartons used to package customer orders. As in, does the online retailer supply their own boxes or do we as the 3rd party fulfillment provide the cartons.
The answer is actually that it can work either way. Most fulfillment centers will stock a variety of sizes to accommodate a range of product sizes. Because these specific sizes are being bought in bulk for several customers by the order fulfillment warehouse, they are typically available to the clients at a lower cost than if the client were to purchase the cartons themselves. If a client requires a "non-standard" size that the order fulfillment center does not stock, they'll often buy them on behalf of the client and mark them up slightly to cover administrative/ carrying costs (10-20% is not unusual).
If a client wants to supply their own cartons, or use free cartons, provided by a carrier (like USPS, FedEx, UPS) then the fulfillment center may charge an assembly fee ($.20 +/- per carton) to cover labor and dunnage costs to build the box and prepare it for shipping.
If you are shipping a food product then packaging become a bit more complicated and insulted cartons will easily run 3 to 4 times the cost of plain corrugate.