The policies at DeckBox seem in line with what is generally accepted. For comparision, here are the guidelines from PayPal (I've clipped some that are irrelevant):
Seller Protection
If you are sent an unauthorized payment (for example, from a hacked account) or a buyer claims they never received their item, our Seller Protection covers you for the full amount of the payment on eligible sales. For more information, see user agreement
Protected Sales
Tangible items that are sold and shipped with proof of delivery from within the United States to buyers worldwide. To ensure you’re protected, ship within 7 days to the address that the buyer specifies during checkout. Be upfront about all the details of the item, specifically defects, use, and abnormalities. Also disclose an accurate delivery estimate.
Proof of Delivery
Required for protection eligibility. A digital or physical proof of delivery from the shipping company that should include: ship date, buyer's address, and delivered date.
Items Not Covered
Items that don't match your description, intangible items like services or digital goods, items that violate our or eBay's policies, and items you sell or deliver in person. All are not covered.
Tips
For payments over $750 USD (or local currency equivalent, including shipping and tax) or more, be sure that you have signature confirmation of delivery in addition to proof of shipment (See above). If a buyer files a claim, you must respond to our requests for information as outlined in our communications to you.
You ship the item to the shipping address listed on the PayPal Transaction Details page. If you’re not selling on eBay, make sure you ship to a Confirmed Address. This means that you’re shipping to an address that PayPal has validated to help reduce chances of fraud.