brinked - 6:42 pm on Mar 1, 2010 (gmt 0)
I have been focusing more on the link buyers rather than the link sellers.
I have never sold links before, so I cant really offer much input as someone who has much experience with this. HOWEVER, I have seen websites that have high PR, and then suddenly their PR drops to 0 but they stillr etain their rankings...so I would believe that if you get caught for selling links, your rankings will not be effected. Your "privilege" to pass link juice to other sites will be removed. This will hurt you in the sense that nobody will want to buy links from you anymore and your earnings from selling links will vanish.
If your site has lost rankings, it might have nothing to do with selling links. Again, I have never had a site that I sold links on and I never experienced google removing my PR but I would like others who have experienced this to share their experience.