I manage a commercial publishing archive in which we house and curate some 3rd party publisher's collections, along with all of the services that comes with holding an archive deposit. We also provide a cataloguing, library, enquiry and courier service for them.

We are at the point of renegotiating terms and conditions and I was wondering what a typical service charge would be, once we have worked out the directly attributable costs. The initial thought was 20%, but we do provide a unique service in many ways that they wouldn't get elsewhere. 

Does anyone have any experience or thoughts on this?

Kind regards

Charlotte Heppell