Use this knowledge to understand your conversion rates per ad spend. If you spent $100 to make $800 then you made $8 for every $1 you spent. Conduct more tests, then scale out your efforts using the Pareto Principle, or the 80/20-Rule, which states that 80% of your results are coming from 20% of your efforts. Use meticulous tracking to discover the efforts that are leading to the biggest results. Simple as that.
However, please bear in mind that you don't need to just spend more money or target a larger area to increase traffic — optimising where you're targeting can do the same without spending any more money. You can get quite granular with your location targeting, even excluding specific post codes if for some reason you don't want your ad appearing to those people (and costing you money).
Buying website traffic shouldn't be a replacement for SEO and other conventional methods of online marketing, but it can certainly give you that edge you need in the highly competitive online market. You can improve your Alexa ranking, time on site and lower bounce rate, but most importantly - it will drive potential clients and bring your website in front of your target audience long before you will see the first results of your conventional marketing strategies.