Articles on Herbs/Herbal Supplements

I need articles on medicinal herbs & herbal supplements. All articles need to be well researched and ORIGINAL.(No cut and paste or plagiarism) I will test its originality on the web. My budget is around 2-4 USD per article. For good writers this could be a very big and on going project. Around 600 articles in total. Each article will be around 500 words. More detailed list of article topics will be supplied to the successful bidder. Please attach a SAMPLE writing with your bid. All articles must be SEO/keyword optimized with 2 to 4 specific keywords. Keyword density will be around 2-3%. Specific article topics and keyword guidelines will be provided to the successful bidder. All articles must be approved before they are accepted. If an article does not meet required specifications, the writer is obligated to edit and correct to bring product up to quality and readability standard. Final articles must be free of typos, spelling and grammatical errors. Each article will be delivered in MS Word format. We will have exclusive right to edit, format and use these articles at our discretion. The articles must be exclusively for me and not to be resold to others. The articles should be informative and easy to read, following web content writing style (sub headlines, bullets, short paragraphs and etc.) I am looking forward to receiving bids from serious bidders and those who agree to the terms above only. Thank you