I can tell you from my experinece with pokernews that it really depends on the writer and what they bring to the table. If I wrote a poker article for you to post on your site, sure it would be content, but really that is all it would be..... I'd say $10 tops for my articles on poker strategy.
Now if one of the top online pro's or even a poker writer like John Caldwell wrote an article, it would be worth a hell of a lot more.
I suppose you have to look at it this way; Are you trying to just add content, or are you trying to have an actual writer add value to your site.
Personally I think both are fine, it's just a matter of figuring out the worth of who is writing for you. Just my 2 cents, but I think it can range from $10 - $150 per article.