I have been buying and selling on ebay for over 6 years and during that time I have come to the following conclusion.
Paying for your item via paypal is the best possible way. However, paying with your credit card using paypal is the most solid protection.
If you pay for your items (big ticket items) via funds available in paypal or via your bank account you are really at the mercy of the seller, because if you buy, for example, a $300 PDA and paypal offers $200 protection for buying from that seller and then something goes wrong (item gets lost or item not delivered) and paypal rules in your favor, you will get $200 for sure from paypal. the remaining $100 you would get only if there are funds in the seller account, well from my experience, if someone is selling something they do not intend on delivering as advertised, they are not going to keep the money in their account to have it reclaimed by paypal in a few days. However, if you pay for the item by a credit card (make sure you check with your credit card issuer if they have an online purchase protection policy and make sure to check the terms of that policy), then you are covered under you credit card issuer's online purchase protection policy.
I had an instance happen to me where I bought a $500 walmart gift card for $400 and paid for it using my credit card via paypal. Of course the card never showed up and the seller never responded to my emails. after a few weeks of investigation paypal refunded me $200 and I was told I would get the rest if paypal was ever able to collect from the seller. I contacted my credit card company and they opened their own investigation into the matter, a few weeks later I got a refund from my credit card for the other $200. Have I paid for that card with paypal funds or bank transfer, I would still be out $200 today.
To use your credit card, you first have to add a credit card to your paypal account (the credit card can only be the secondary fund source and your bank account is the primary) , then when its time to pay, you need to withdraw all funds from your paypal account and then you need to make sure to select the card as the primary source of funds when making that payment. MAKE SURE to select the credit card as your primary source of funds each time you want to pay for an item as each time you process a payment the funds source resets to paypal - bank - credit card in this particular order.

Good luck