For those of you who looked at the recent advertisements from the different part vendors on this side of the pound, I ran into the following web page on the other side of the pound that seem to list a much longer list of Workshop Manuals:
So far, the cheapest "Defender 90 NAS" CD of this kind, I have found is on Expedition Exchange web site (no previous experience with them, but I assume they are a good vendor).
I figured that this might be useful for someone.
Disclaimer: I have no experience with those manuals. I read that they only work on the PC machine, do not work with Windows Vista. They also include some security features. I am still unclear if you can (or not) print the pages [Which is a big no-no for me.... I'm not going to bring a computer in my garage or while I go off-road]