Clarify the condition in writing. New, open-box, used and refurbished describe different situations; the price comparison should reflect them. With a used console, test normal operation, the controller, the relevant ports and any disc drive. Confirm that the device has been reset appropriately and can be set up with your account. Unexplained restrictions or a seller's insistence that you must keep using their account deserve resolution before payment.
Keep the invoice and exact console model details. Ask who provides warranty support, what is covered and how a problem is reported. A generic promise of a warranty is less useful than a clear process. Verify what the box contains and whether the cable, controller and supports match your expectations. On delivery, inspect promptly and follow the retailer's reporting process if something is missing or damaged.