I got my SBZ (non oem with gold caps) new for £48 pounds (from Amazon). Use this and keep your fingers crossed: http://uk.camelcamelcamel.com/search?sq=sound+blaster+z. Don't worry about the gold caps. It's a great card on it's own and I don't think you'll be disappointed.
As NoOneLt says .. the ZxR will sound better for music, but be about the same for games in surround.