Purchase Order Unit Cost Security

We want users to be able to check on PO Statuses, PO Expected Dates, Quantities, etc, but not see the Unit Costs of each item.  I looked at all the Security Events and module options but I don't see a way to do this.  Any ideas?

A question involving Explorer views - to see them, you need access to the tables, correct? If so, if I create a custom PO explorer that does not list Unit Costs, how would I handle security then?  For this group of users, I would want to exclude them from PO and IM completely, so they can not drill down to the PO's and look at the costs.

Or just create a custom PO report?