Locate the item you want to resell in the search results and then either click the “Resell” button at the bottom of the screen or select “Resell” from the right click menu for that item’s row.
In the “Resell Offer” dialog enter your markup. This is an additional percentage added to the price and paid to you when the item is sold. The initial item cost will still go to the root seller, who is also usually responsible for item fulfillment.
An example markup value is 5 for 5%. The minimum value is 0 and the maximum is 500.