I'm sure the cost of a license is going to depend upon the number of seats using it, in any case I always contact the vendor for that. Then there is the negotiation process...
You might want to consider factors such as what features are currently used, which are important and how do instructors and students feel about them. A survey might be in order (use www.surveymonkey.com ? it's easy to set up, easy to use and provides good data). Don't underestimate the cultural factors of an institution, personalities, history, preferences can all make or break a project.
You can install Moodle on a PC for testing if you are uncomfortable with Linux. There are some pretty good instructions out there and it is low risk. You will need to install an Apache server, MySQL and PHP - but this might be useful experience. The O'Reilly publication 'Using Moodle' is probably version 1.5, but easy to use - maybe a used copy? What better demonstration than a walk through on your laptop or projector?
Best of luck.