Outsourcing dominates the Search Engine Optimization (SEO) copywriting business simply because writing bulk articles is the nature of the business. There is a big demand for multiple articles to be submitted to search engines as portal pages as well to ezine article directories and blogs. When you have a big job, outsourcing makes sense because the articles can be had for cheap. SEO copywriting often entails the writing of twenty or more articles (even hundreds of articles) about one particular subject. If you are busy running your ecommerce business this means that you might have to outsource this material to a freelance copywriting service.
Many agencies and auction sites online provide outsourcing from companies like India. Many of these companies have their own site on the web. They are also a strong presence on guru.com and elance.com where they are able to underbid North American copywriters by bidding for jobs at 95% the going writer union price. Outsourcing your copy written material to India is a very viable solution as long as you don't care that somebody who can barely understand English may write your articles. However all that matters here usually is that the keywords are in place so that the search engine can understand them.
Whether you choose a North American or Indian provider is probably largely dependent on the purpose of your articles. If they are more meant to be search engine spider food, then outsourcing them to India is a cheap solution. However, if you feel that the language barrier could be a problem and you are more interested in the subtle crafting of your material so that your SEO articles are reading in what advertising copywriters call a "naturalized" fashion then you are probably better off to hire someone who is more local.
Outsourcing sometimes make a lot more sense in terms of time vs your cost.