If you like to get art books are great prices, always look for the bargain price box. It should look something like this:
That's the bargain price for The Art of Robots. It's selling right now at the time of this writing.
That book is selling for US$30, but the bargain price is only $US15. It's less than half the retail price.
Titles I have seen carrying that box were The Art of Pirates of the Carribean, The Art of The Incredibles and the Art of Finding Nemo. All of which were sold out already.
My colleague once bought the bargain price version of The Art of Pirates of the Carribean. I couldn't notice anything different from a brand new book. That said, it might be different in another purchase.
It's worth it to look out for that box.
By the way, The Art of Robots is a great book and I have the book review on my blog.