The power of social networking.
Example: What would you rather have.
Your own 40' Houseboat.
Access to a 40' Houseboat any time you want?
The best answer is "Access". Why? Because you don't have any of the downsides.
Now how does this apply to the question? Like this: Creating compelling content that others will distribute for you is much better than having to create your own distribution channel (Marketing yourself). This is the concept of leverage.
So now let me get to the point (Without buying ads)... if you want to "Market on Facebook" do this:
Find your Target Audience.
Find the most popular people in that Audience
Make friends with them.
Post non offensive directly related comments (Not links) on their wall so that like minded people can find you.