Hi,
We currently sell an ebook version of our Sentence Correction guide for the Amazon Kindle (you can see it here:
http://www.amazon.com/Sentence-Correcti ... ref=sr_1_5 ) We're also working on converting our book so we can get other e-book formats out, but so far we have either the Kindle version or the hard copy.
Unfortunately, we cannot offer a discount for the purchase of a single book, but we do offer package discounts if you were interested in buying more than one book. Also, if you ever choose to take a course with us, you can always get book credits towards the course for the books you already have.
Best Wishes,
Caitlin Clay
Student Services Associate
Manhattan GMAT