Running sites without a db can be handy - for instance if you don't have a db ;-) It's easy to host them almost anywhere for almost $0 - easy to scale if that's an issue too. There's generally less security to worry about, not so much worry about upgrades, patches etc either.
Whether statamic is worth $199 to you is another matter though - it's certainly a bit friendlier than some of the other static site creators. I used to use pelican as I got fed up dealing with wordpress - but it's not as easy to use as statamic from what I've seen.
In my opinion, Wordpress is slow and bloated. I avoid using it unless a client asks for it. Statamic is awesomely easy to use. IT is documented well and is super fast. However, if you are set on free then give a good look to PyroCMS and OctoberCMS. Between the two, I think PyroCMS is better because it is fresh and actively developed using the latest Laravel code.
