By doing what Davewil said, it will give the buyer a black mark against their name. A lot of buyers set their settings so people with black marks can't bid on their items. To prevent people with black marks bidding on your items (they have to have at least 2 in (I think) 12 months), go into your account settings, then click on site preferences. Go down to 'buyer requirements' and click 'show', then click edit. Tick the boxes that you want to apply and adjust the numbers accordingly. The black mark option, I have it set to 2 unpaids (minimum) in 12 months.
Good luck, there's nothing more frustrating as a new seller having someone who doesn't pay. I've only been selling again since Feb and even though I don't sell a lot, I still get at least 1 non payer a week. I was always worried about people with no or little feedback, but they seem to pay straight away. It's the ones with several hundred that are my worse offenders.
