First, you need filter very good every Ad Facebook - One ads for every gender, for age ranges, for common interests of products similar to your brand, for language and last for demography. If you do it like that, $ 20 can reach enough people. While it is true, that more money more people.
Use Gadget Flow to both gain traffic and increase sales if your budget is sufficient enough to afford their services. Or submit your project to BackerLand if you don't have much budget. This platform works even with a limited budget while still providing a reasonable ROI.