Don’t ever buy comment link building for SEO. Why?
Leaving the same comment in short period and in the same article is not a good method. Automated comment link building will lead your website to Akismet spam folder. You may get few first comments approved. However, when more and more people started to mark your comment as spam. In the end, all your comments will in spam folder all the time. Does it worth the price?
Personally, I won’t purchase this kind of service. And Google does not like it too. I believe most of us don’t like our blog being spammed by these useless comments, right?