PCI quarterly network scan cost?

["Custer, William L. Mr." <custerwl () MUOHIO EDU>]

Institutions that do PCI self-assessments must have quarterly network scans done by PCI certified vendors.

I am told that that cost of such assessments is based on number of IP's.

Does anyone have vendor actual or estimated cost for such scans.  Include the number of IP's in your answer.