Akamai is a cloud-based platform that provides CDN services as per your business needs. Thus, its pricing is customized and they bill their users on a "pay as you grow" model. As the traffic grows, the pricing also scales.
Coming to your requirement, Akamai (as found on the internet) confirms that they charge $350 per TB. This pricing continues till 10TB ($3500). Id suggest you go for their free trial period (60 days) and see how well it fits your requirement. You can also contact their sales team to get you a good quote on your specific requirement. Hope this helps.