The Media Martens are designed to create a fair exchange between the customer (the person who owns the Media Marten) and the seller (the person selling their used media).  The process allows the seller to choose which type of credit card account will be credited by way of an automated clearing house (ACH) transaction.  Typically, the Media Marten owner will verify that the item sold is the same as the one described prior to authorizing the transaction.  One of the most immediate and secure forms of credit card use is with PayPal.  You can use your PayPal account without a PayPal debit card, however, like any ACH, it takes 3-5 business days to transfer the funds to your bank account.  You may want to consider setting up a PayPal debit card.  Here is the Why and eHow (taken from eHow.com):

"If you use PayPal, the online business that allows you to accept and make payments through an Internet account, you may be interested in a PayPal debit card to help you access your money. While it may take up to four days for a transfer from your PayPal account to reach your bank savings or checking account, PayPal debit cards allow you to get your electronic funds from an ATM or at a participating retailer immediately. Use these steps to get a PayPal debit card."

Instructions

• 1. Sign up online for a PayPal account so you can get a PayPal debit card. Although there are three account types (Personal, Premier and Business), you’ll need to sign up for a Premier or Business Account to get a PayPal debit card. Unless you own a business or conduct frequent business-related transactions online, a Premier Account should suffice. (Each member is allowed to have a Personal Account and a Business or Premier Account.)
• 2. Ensure you register for a Personal Account first, even if you plan to upgrade to a Premier Account to get a PayPal debit card. After getting to the Create Your PayPal account screen, simply enter your country and language. Enter current information including your name and the primary email address you’d like to give out when you make and accept payments via PayPal. You’ll also need to enter your name, mailing address, birthday, phone number and a password.
• 3. Confirm your account by linking a valid checking account and credit card. (If you’re signing up for a PayPal account for the first time, you’ll need to wait until two small payments are made to your checking account so you can confirm the transaction to validate your PayPal account.) Once you’ve successfully signed up for the Personal Account, you can upgrade to a Premier or Business Account.
• 4. Get a PayPal debit card by clicking on the “Debit Card” link at the bottom of your PayPal account screen. You’ll need to confirm your mailing address before PayPal will send the debit card to you. The mailing address must match the billing address on the credit card you’ve linked to your PayPal account.
• 5. Follow the directions that are mailed with your PayPal debit card to activate it before use. You can do this by logging into your PayPal account, navigating to the Profile screen, pulling down to the PayPal Debit Card entry under the Financial Information tab and selecting Activate Now.
• 6. Read the PayPal stipulations to ensure you know the current daily withdrawal limits from ATMs (typically a four hundred dollar daily withdrawal limit from ATMs and a three thousand dollar daily spending limit), fees for accessing your funds through an ATM (typically one to three dollars) and current cash back bonus rewards for using the PayPal debit card like a credit card at brick-and-mortar retailers.