Just Wondering

OK I am new to this and trying to find a good program to make some e-books. I have some great ideas for some exam prep course e-books that I think will sell very well and in the 100.00 to 200.00 dollar range.
My big question is how well do people do with good e-books, I know thousands of people a month take two day courses for this exam. But how well do people really do selling e-books.
Is there any people out there that would mind giving a idea of the volume of business they have done. I have seen people claiming big money but it usually comes from someone pushing there E-book software. Thanks for any one that could help me.