Content writing project for long term : 1$ per 500 words

We are looking for content writer for 3 websites in domain of health, medicine and pharma. Requirement is to deliver an article per day with 500 words each. Each article has to be self-written, copyscape passed, written in proper US / UK english. An article which is not copyscape passed will not be considered as valid article for project. Current requirement is for 30 articles. Order size will increase based on quality of work delivered. We are willing to pay 1$ per 500 word article. Payment can be via GAF or paypal in parts at regular intervals. People applying for the same must have experience in health industry(medicine, pharmacy). Samples appreciated. Promptness and originality is the key for the project. Queries will be entertained over PM.