It depends on the traffic. There is CPC and CPM, as two industry standards.
CPM is cost per 1,000 views and CPC is cost per click.
Generally you charge a price based on the topic of the website and the ad being shown. If your website is about gaming, a banner ad for gaming computers is probably worth more than a website about writing with an ad for pens & pencils. It's all about what your website's topic is & how much the products are worth that your visitors are interested in.
Generally people will not be interested in purchasing a banner ad for a large amount unless your website is getting tens of thousands of views. Many people go for Google ads or another network because it's easy to manage & shows visitors what Google knows they are interested in.
