Yes, Invision is more expensive upfront. However, if you factor in the relative cost for each application, it’s actually cheaper.
XenForo costs $335 upfront (if you get every application) and you get forums, media gallery and resource manager. $111 each.
Invision Community costs $499 upfront and you get forums, commerce, pages, downloads, blogs, events, and gallery. $71 each. You also get Clubs too.
Now do you need all those applications? Maybe not, but that’s for you to decide.