FSI on Amazon

Hi
I've just noticed that Amazon is selling the Vietnamese course with a CD or as a kindle edition. I was surprised to see it on the site and I wonder if the audio or workbooks would be any different from what is available free here. I have the workbook on my Kindle DXG using Duokan OS but would like to have easier search/navigation if it was a proper e-book and not a PDF.
Cheers
Michael
I've just noticed that Amazon is selling the Vietnamese course with a CD or as a kindle edition. I was surprised to see it on the site and I wonder if the audio or workbooks would be any different from what is available free here. I have the workbook on my Kindle DXG using Duokan OS but would like to have easier search/navigation if it was a proper e-book and not a PDF.
Cheers
Michael