I think the license for v-bull is 200 bucks. (per year?)
But its updated relatively frequently, and seems to be relatively secure… start by reading the wiki for vbulletin - http://en.wikipedia.org/wiki/VBulletin
and become a little more familiar with it. Then present your reasoning to them after reading that.
and good luck on stealing it:
ICANN Registrar: NETWORK SOLUTIONS, LLC.
Created: 1997-01-29
Expires: 2012-01-30
You may just want to ask to help out or pay for the license for them… or have a group of people pay for it
edit: http://en.wikipedia.org/wiki/Comparison_of_Internet_forum_software
another good read if you really wanted to present a comparison to what vbull has to offer over the other software which they are using