Regarding monitizing: Please remember that you can also make skin edits. Besides of that there is also advertisement intergration(pre-set locations where you can easily insert advertisements from the ACP :) )
Regarding the no refunds of vBulletin: I highly recommend to look up your local laws, consummer laws(EU laws for example) require refunds for products, including but not excluded to software licenses :) This might especially be true if the product they sell does not function as advertised(impex for example).
Regardless, you might wish to consider IPS products, I have licenses of both products and honestly, IPS hasn't let me down yet :)
I put in a few questions where I don't know the answer of as this was the only way for me to fill them in a way that others won't be able to guess the answers ^^' The issue is, I don't even know the answers myself so I will have to guess them(The closest guess is correct though :P ).
I recently got some odd licensing issue that resulted in some of my unassociated licenses lost due to a update to the licensing system. To my surprise the person that assisted me was Lindy(CEO). who quickly resolved the issue.
The way the issues had been resolved was above expectations, you don't expect the CEO to answer on your ticket. - Lindy even noticed some more lost licenses and restored them!
You don't expect a company to highlight additional issues and resolves them, especially as not highlighting them might result in more license sales. By highlighting it IPS has proven to me once again that they are willingly to take that "One' additional step for their costumers :)