I'd agree with the others here who say that doing it yourself is the way to go. Really, you'll end up spending more money to get someone else to do it, and if you buy one off the shelf you are totally at the mercy of what someone else has decided to write, and write about. If you write your own content you'll get a feel for it, and the less you outsource the better a feel you'll get for doing it yourself.
If someone is selling micro niche sites you maybe have to ask yourself why they're not keeping hold of them themselves. Sure, maybe they're not so much with the link building and ranking stuff, but that does mean they're less likely to be invested in the quality of the site.