Fusion5 -Hi -I sell Retro and Vintage items in my eBay shop,everything from Victorian to 1980's kitsch (rubbish lol!). I also have a 'real' shop.
To block bidders who regularly don't pay do this:
In summary go to Account -site preferences-buyer requirements.Click 'show' the 'edit' and follow instructions.
many businesses on eBay do this which is the only way you can get back at bad buyers. Thats why you should always do an 'unpaid item' case through eBay rather than cancelling an order,as when they don't pay they get a mark against their user name and once they've got a few they can be banned.