Concentrate in getting qualified fans. Use that money in Facebook ads. This is the best way to grow targeted fans that will engage your page. If you look at any page with influential number, you will see a engagement rate of less than 1%.
I know it's cliche, but quality over quantity. Having 100 fans that are engaged is better than 1000 fans that will ignore you.
Through ads, I have discover new segments of client to which target by analyzing my real fans profiles. This is a great exercise that will help you create better content and have an active page.