Dean
in memoriam
Unfortunately, if you allow paid add listings there will be a much greater incentive for coders to charge for their creations. I think you would see the mod community move farther and farther towards the 'paid' end of the spectrum. While this would be alright if everything produced was top-notch, I highly doubt the mods would be of a higher quality than their free counterparts.
On our forum, the advertising cost is significant, and the market takes care of the balance of free vs paid. People choose the free solutions, unless they have a significant reason to buy the paid solution. And that results in higher quality paid solutions.
If the advertising was inexpensive, that would create the problems you suggest. On our forum it generates significant income, although I wish it was more.
It was just an idea, in case no one had mentioned it. I see no paid advertising on vb or ips.