Question

your reading material traces an example that shows how a giant like wal-mart can make it difficult for small sellers. In this case profiled, Wal-mart was able to sell a harry potter book for _____

Answer 1

Because we do not have the same reading material as you do, we do not know the solution. In addition to that, you are posting the question in the wrong section. This is an economics question. Refer to your required text for the class for the solution. 

Answer 2

Answer:

The entire Harry Porter Series cost $49.96 at Wal-Mart.

This is $3.04 less than their smaller competitors who sold at $53. They are able to do this because they understand how to utilize economies of scale to their advantage.

Is this ethical or not?

That is not the question. The forces of demand and supply have are amoral. It's a question of strategy and execution. The company with the best combination of both subject to the 'favor' of all other forces external to the business operations will nearly always win.

Cheers!