Whilst surfing around, I came across GetCertify4Less. Now, these guys appear to sell VUE testing vouchers at a discount, sometimes over 50%. Some of the vouchers have expiry dates and they do appear to be legitimate. I have read reviews of people who use them with no issue.
They have exam vouchers for Cisco, Microsoft, MOS, Novell, Check Point, IC3 and HIPAA.Check them out at http://www.getcertify4less.com/ and see what you think!