Since no one has mentioned it yet, I want to point out that pricing depends on the volume you purchase.
Here is a link to IBM's software catalog where it shows the list price:
https://query.lotus.com/passport/eorder/Express?P0=E1&part_number=D5CPILL,D5CS2LL&catalog_url=http://www.ibm.com/software/info/ecatalog/html/lot_msg-coll.html&country=USA
Note that it does not reference a platform; as someone else pointed out, this is simply a client access license and is not platform specific.
HTH,
Charles