It's 35 dollars a year to renew your license which gives you access to the Mod/Hack section, and future updated releases to VBulliten, which are mainly security updates and other features.
There are hacks such as
vJoomla which integrates Joomla and Vbulliten together which is quite nice. Joomla being a widely used program for main portals on websites. There is also
VBadvanced CMPS which you can enable as your main page as well and it displays recent posts in certain sections of your forum.
The main reason I chose VB is because I'm more comfortable with the security issues. As a board grows its wiser to have stable security setup for all the hackers that want to ruin your site/forums.