My friend bought the cartier sunglasses two years ago for $ 160 on her business trip in america. You could buy one from the online store and buy one. But you should check to see whether they are authentic. Usually the price in the online store is cheaper than those in the franchise stores.
It is really expensive to buy cartier sunglasses. I saw online that most of them are over $900. But i also see some people said that cartier sunglasses are ranges from $800 - $5000 depending on different styles, frames materials etc. And if you have no idea where to buy, you can try to search them out from online such as eBay.com
Well, they are kind of expensive for many people, for example, they can cost you $1000. But on the other hand, it all depends on what type you want to buy. As you know that they are made in Paris, France. And they are the brand which is very famous for its quality and beautiful design. Because of these factors and they also have different kind of styles, the prices are also different. So it can be very different. Of course you can buy them in the real stores so that you can make sure if they are suitable for you or not. But in my opinion, you can buy them on online stores which are cheaper than the real stores. For example, you can buy them on eBay, which is a famous online stores and it can provide you many types. In addition, if you are not sure if they are authentic or not, you can just bring them to the sunglasses stores where they can provide you a professional advice.