I think the hardest thing to overcome is that it is really hard to get people to pay for something when they already had or have access to it for free. (i.e. YouTube). That said, I am all for paying for additional ads as you need them, or even all of them. Look at eBays egregious 12% cut. I also think organizing into sub sections would be a great help, so you don't have to sift through things unrelated to what you are looking for.