The cost of backlinks can vary widely depending on various factors such as the quality of the website, the authority of the domain, the relevance of the content, and the link placement. Generally, backlinks can range in cost from a few dollars to several hundred or even thousands of dollars per link. It is important to note that purchasing backlinks is against the guidelines of search engines like Google, and can potentially lead to penalties or a decrease in rankings. It is recommended to focus on natural and organic link building strategies instead.