You will not find higher-quality training material for business writing, and the price is unbeatable.* Basically, you can't go wrong.
The price for a site license is $200, plus $1 per employee for the first 100 employees, plus $0.10 per employee beyond 100 employees (includes all employees in the company).
* Here are some reasons why this training material is the highest quality:
It is designed for students to use while writing with pencil on paper. People become better writers not by reading rules in a textbook or by checking off multiple-choice questions on a webpage. They become better writers by actually writing. This is best done with pencil on paper. We learn best when we are relaxed and when we are using more of our senses: sight, touch, and smell. We are more relaxed and more involved when we are holding a pencil and paper than when we are typing away, staring at a computer screen, getting more and more tensed up by the minute. Do you feel relaxed right now? As relaxed as when you are sitting back, reading a good book? Be honest.
It doesn't just say, "Here is the theory, and here are a few simple exercises with solutions." It provides many challenging exercises with solutions. In the challenge lies the possibility of making mistakes, and in thinking about our mistakes lies the real chance for real learning.
It doesn't just say, "Principle means this, and principal means that, so try not to get them wrong." It provides clever memory aids that people are unlikely to forget. This is especially helpful in these Lessons: Apostrophe, Grammar Gaffes, Words Misused, and Idiom.
It teaches advanced concepts in the Projects, but presents them in writing exercises that are easy to understand, fun to work through, and challenging enough for students to attack in groups in an advanced writing workshop. If you sent employees to a writing workshop that taught these concepts with teaching content of this quality, you would pay more than several hundred dollars per student, per day.