If you are going to pay with your credit card, don't go through PayPal but pay the company directly with your credit card.
The law (s.172 Consumer Credit Act) requires credit card companies to make good any losses that arise when purchasing goods with the credit card. But the payment MUST be directly to the seller, not a third party such as PayPal.
Some credit cards voluntarily apply a similar protection to PayPal purchases, but not all. So unless you are very sure, do not rely on it before spending big money on eBay.