Yes it is very possible, this is how I first started earning money online, I now charge $10 for ~1000 words which will take me about an hour to write. the best places to find this work are forums as stated above.
-There are about ten active webmaster forums that you should sign up to and check daily to make sure you are the first person to contact the advertiser.
-Make sure you have a portfolio ready for the potential client (links to about ten of your highest quality posts)
-If you don't have a portfolio yet, do a few articles for free, dedicate a few days to it, make sure they are high quality and don't include your backlinks. If you're good enough the person you are doing them for free for may pay you to do more.
-NEVER COPY OTHER ARTICLES this will get you absolutely no return custom and return custom is where you make your money, when people are coming back to you asking for another article you can bump the price