"Unique" is a relative term. You can always get away with PLR articles and a spinner. You don't even need to hire a writer. Go to tradebit.com and buy those article packs. 15,000 articles in 200 niches for a $1 or something like that. A lot of people dump them there. Then get a spinner. And you can turn those articles into all the content in the world you'll ever need without ever writing anything yourself, or hiring a writer. Its hard to hire a good writer, btw. Those who write articles for $2-3 aren't even worth considering because of poor english. And at $10 per article it can start costing you money pretty fast.
Using unique content is key to your success either you write it on your own or you hire someone for writing.