Why did he have to pay (again) for that image?
Obviously they are public domain since (we the public) paid to have the original images taken.
From the NASA site:
"Many NASA images and most film and video footage are in the public domain can be used for advertising purposes."
As far as a high quality image of the entire earth, there is one very hi-res version (not vector though) on the NASA web site, but I'll be damned if I can find it now. It prints at 54x54 just fine.