An e$-$commerce marketplace startup is selling products over facebook. The facebook advertising cost is USD $200$ per $1,000$ impressions. The clickthrough rate is $1\%,$ this means that $1$ out of $100$ facebook users click on the facebook advertisement, and visit the website. Out of every $10$ visitors to the website, only $1$ visitor buys a product from the startup.

What is the customer acquisition cost $($CAC$)$ of this startup?