you can use wallbase batch downloader http://wallbase.cc/forum/topic/1793 although 1.4 million wallpapers may take awhile

....you might not want to download all the wallpapers in wallbase, because that will take an immense amount of time and will consume a lot of resources....
However, if you're intent on wasting a huge portion of your time and resources, then as koalafishy said, WBD.

Once again, though, I don't recommend it.

Right now, there are 1,469,023 wallpapers. Good luck with that.

lol I like wallpapers but i think 1.4 mi wallpapers is a little too much

With over 2000 wallpapers getting uploaded, edited, deleted everyday good luck in your quest. You will need it.

This topic is a waste of time.
Closing....