Text Analytics APIs 2018: A Consumer Guide is $895 for a single user license. At 299 pages, that’s about $3 per page. The blurb notes that:
Robert Dale is an internationally-recognized expert in Natural Language Processing, with three decades of experience in academia and industry. With a PhD from the University of Edinburgh, he’s worked for Microsoft and Nuance, and he’s driven the development of SaaS-based NLP software for a startup. He has taught at the University of Edinburgh in the UK and at Macquarie University in Sydney, and presented tutorials and summer school courses around the world. He has over 150 peer-reviewed publications, including a comprehensive Handbook of Natural Language Processing, and the de facto textbook Building Natural Language Generation Systems.