blog commenting (high quality post required)

I need blog comments. I have made the blog pages list i want you to put a comment on. The blogs are related o link building, SEO, blogging, marketing... Yo must have a good knowledge in this field. I'm looking for a blogger to do this project, someone that s in this field and that does it a lot for his own blog, that will be the best. Or at least a good copywriter could do the job too. I'm paying $3.50 per succesful posted comment. Comments have to be from 50 to 70 words each. I'm not looking for someone that will spam blogs, but for someone that first read the content, and add a useful VALUABLE comment. My site reputation can't be ruined by a spammer saying BS with my site name. 1) I provide the blog pages list where to post comments. 2) You post 50-70 words useful and valuable comments. 3) You provide a report where i can see the posted comments. Impress me first to get the project. Thanks.