The system allows adding a product line to a price list or all price lists at once.
Instructions
Go to Setup > Price Lists and click on the "Product Prices" link
Click on the "Add Item to Price List" green button.
Select the price list needed to add the item to or select "All" to add the product line to all existing price lists.
Select the season (if applicable, selecting "All" will affect all seasons by default), product and price.
Select the exception by Vendor and Box type if needed. Those options will allow you to determine if the price applies to a specific vendor and/or box type. If the vendor is left blank it is assumed that the price applies to all vendors.