As an active buyer and seller on eBay, I'd agree with the advice you received here… with one modification. If you think you might elect to continue using eBay, I's recommend going on the the PayPal site and applying for a PayPal issued credit card. One with just a low limit… maybe $1,000 or so (I'm in the U.S.).
The advantage is that you can use the PayPal credit card to pay for things rather than accessing any funds you might have in the PayPal account (which you have to supply with a pre-existing credit or bank card anyway). I would never put my bank card number or even a higher limit personal credit card on a public site. PayPal has a pretty good reputation so far for security, but if you have your bank card as the source for supplying PayPal with funding for you purchases, you run the risk of having one of your most prized possessions open for hacking, leading to access to your check, savings and other such accounts as you may have... Where as, if the low limit PayPal card was hacked, not much loss and I'm sure PayPal would pay for such loss anyway…
Good luck!