I am currently engaging with Segal Consulting for this purpose for our organization.  I found them on the web and submitted a request to be contacted and went from there.  Good luck in your research!

Sara, at HR Partners, we do quite a bit of compensation consulting. I'd be happy to talk about your needs and options. Reach out to me at darlene@HRPIInc.com Darlene Mack, MA, SHRM-SCP, SPHR.