When you have resorted to paying for leads, clicks, ads or other ways to buy the first stage of your marketing funnel, you need to make sure you get the most out of it.
Every time you pay Google or another PPC provider for an add, get:
An actual lead into your funnel (use negative keywords, good landing pages and clear call to actions to make every click count)
Use every click to test something. Each time you pay someone say $3.50 for a click, you have an opportunity to learn something. Each Ad should be an A/B test providing you market research feedback.
Amplify great content that over time could rank organically. Not only should your landing page for the click be good so it will actually convert people, it might actually be something people will share and thus become organic content over time.
Make every PPC dollar you spend count by letting it do three jobs instead of one.