What more could I add to my offer?

Greetings Group,

At one of my websites, Get-This-Report.com I've been selling a book I wrote.

I want to boost sales, but I just can't decide what type of bonus to add. I want to keep the subject matter somewhat in the same ballpark, if you know what I mean.

For example, my book teaches the reader how to profit from servicing glass doors. I don't want to offer as a bonus, Copy Writing Secrets of the Master Gurus. They don't go together. You know what I mean?

I could really use some ideas here.

Thanks for your help
Woody Quiñones
The Promotional Guy