Yes, the €87 is a once off cost for Outlook 2002, these licenses are perpetual. Microsoft got rid of upgrades through licensing last year and have introduced Software Assurance, this is like a maintenance charge that you pay when purchasing your license and then this covers you for upgrades for two years. I have included the price of the Outlook 2002 with Software Assurance cover for two years below. However if you buy the Outlook 2002 licenses now and are only using Outlook 2000, when you decide to change to Outlook 2002, you will have no extra charge, only to purchase a media set for €35.
Microsoft Outlook English Lic/SA Pack MOLP NL - €137+Vat@21%
Once you purchase the minimum quantity of 5 licenses to get you into the microsoft open licensing programme, you can purchase licenses singleythen over a two year period.