I have done reviews for uCertify PrepKits previously:
1) uCertify's PrepKit for SCJP6.0
2) uCertify's PrepKit for SCBCD5.0
Now, uCertify is giving out 20% discount on all its PrepKits. Use promotional code SPRING during the checkout to avail this offer. This offer is valid until 20 April, 2010 and it will work on all uCertify PrepKits. Full details of the sale can be found here.
Overall, it is a good investment if you're preparing for a professional certification. Good luck!