Well actually it depends on the site, so depends on traffic AND pr.

I've sold links on 25 sites I had, so people would get 25 new inbound links for $1 per site, so I made $25 for the total of the sites. I had 5 advertisers, so I made $125 a month. So it is possible, but not easy to sell without having pr and much traffic.

Most webmasters know that you can sell links on your site if you got a high PR. Because a lot of people think that a high pr is thesame as having lots of traffic. Therefor webmasters buy links at HIGH PR sites to increase their own, so they can sell for more $$.

But most webmasters tend to buy links at high traffic sites, to increase their traffic aswell!

Hope this makes sense to all of you!