[spacecoast]

I have the green set on paper and the red set on DVD (a large PDF which is also copied to several computers). I use both as sometimes it's easier to just pull out the book and go to a bookmarked page, but the DVD is nice for searching for terms or for taking a screen shot to post some info. My understanding is that the green set has better pictures and I believe it's also less expensive (something like what you are quoting).

Also, the red set is a year or two newer and does have some info and deductions/conclusions not included in the green set.