Cost-Per-Acquisition (CPA) is the amount of cost that it takes to provoke a sale on your web page. The formula for CPA is total campaign cost / conversions. This is typically used in e-commerce marketing strategies. Cost per acquisition is a financial metric that is used to measure the revenue impact of marketing campaigns. CPA ultimately comes down to, how good your SEO is, and how good your product/service is. The better the SEO is on a website, the more effective your CPA advertising will be. Ultimately, if your site is ranking high on SERPs, you should have no problems reaching the CPA you admire for.