Though Priority Mail is one of my Preferred Methods of Shipping, the reason why Most Sellers use it is Quite Simply, FREE Boxes! Yes, all you have to do is register either through eBay, or directly through the USPS Site, and your Priority Mail Brand New Boxes will be delivered to your door, No Charge. Just select the Size, Shape, Quantity of Boxes you'd like to have for your Auction Items, and they'll be at your door, usually within 5-7 days, No Charge. And, because they're shipped flat, they can be easily stored in your shipping area. Even the Box that they come in are Super for shipping! They used to offer the Best Tape as well, but no longer do without charge. I still use it as it's lightweight, and saves in Packaging/Shipping Overall Cost to the Buyer. After All, the least expensive your shipping is to the perspective Buyer, the Better the chance of a Sale! And Always Pre-Weigh your item before listing, in the Box it's going to go in! Saves money after the sale from Seller Miscalculations, that invariably is the Seller's Responsibility. (or should be!)