Ebook versions in .epub as well as .mobi, .azw and .azk (for Kindles) are now available as downloads for US$15 through PayPal. It is a big download, so fast broadband connections are recommended. After the PayPal payment is finalised, you will be redirected to another page from which the ebook flavour of your choice can be selected and downloaded.
The Table of Contents can be downloaded by clicking here. A chapter on early Neapolitan mandolins can be downloaded here, and an introductory chapter on the Mandolin in America can be downloaded here.