Facebook will only get more expensive as more people (with larger budgets) realize how much cheaper and more effective it is than alternative marketing channels.
If you really don't have a niche you're marketing to at first, you're going to have a bad time with any type of business for this very reason. Your marketing will be too shallow to penetrate any market and won't be able to get traction. You're just throwing away money and have no way to optimize your campaign since you're not trying to reach anyone specifically. Think of how others have done it. Facebook started with students from one university, then students of U.S. ivy league schools, then other U.S. universities.
You need to come up with some specific segment you'd like to have on your site. Just some random ideas -- maybe specific industry or job title. Maybe location. Maybe income. A combination of these things perhaps.
Now people actually have a reason to join -- a social network full of people just like them! Now you actually have some compelling marketing content and demographics to target. That's what you need to figure out first so your marketing dollars can actually work for you.
Once you do that, here are some general marketing tips:
You may need to consider optimizing your campaign to be more aligned with your goals. If you're just looking to spread the word and gain awareness, CPM is the best way to go. As for the ads themselves -- the better your ads are, the cheaper they will be and the more Facebook will show them. They also take into account your entire ad account history and how active/engaging the content on your page has been.
There is a lot more to Facebook ads nowadays -- which means more potential reasons you may not be getting the best results or the best price.
With all that said, I still believe Facebook is the best marketing channel for most businesses and it's probably in your best interests to stick with it.
