Are the selling link sites usually scams? I mean how does anyone sell a link with a page rank 10? It doesn't seem humanly possible since they're all so rare. Most websites are 6 and under.
I have hear this story from internet, Scammer offer you high Pagerank link from very popular website. You have to pay in advance for 1-5 years. You pay him and he buy for you monthly link from webmaster who own this site. Month later link dissapear together with your $1000 - $5000. scary experience isnt it!
And also these days PR is up and down, becarefull buying links simply for PR, you should also see whether the site has sufficient traffic that could spill to your site as well.
Link Selling Websites are not Scams! Buying links is only worth it if you know what you are doing.... Free links are just as effective as paid links, but paid links typically offer many advantages over free links. I do not pay for links very often, but when I do, I spend my money very wisely and I am sure I understand the effect that the link will have on my website at search engines, before I give someone money to post a link on a website.