Spectacular purchase?

Okay, I bid on and won a signed book by Zahi Hawass.  It started out
at 9.99 and I kept bidding begrudgingly (because the book was
dedicated to someone else) up until I finally won it at 40.00 plus
****pping.  Total 45.00.  So I thought I'd check out this book and see
what it sells for unsigned for the heck of it (after I won it).

I was FLOORED. I'll get to the going price in a minute but first,
here's about the book.....  It is a reprint of an 1880's book (first
"re-printing" probably as it's the earliest I see).  1990 with update
by Zahi Hawass.  So the book is NOT a first edition or super rare
(antique).  It's hardcover (increases the value but not THAT much I'd
think) and looks leather but probably isn't (I won't know till I get
it).  It's dedicated to someone else, but the signature is good.

Okay, so the list price?  Used, unsigned copies (with markings etc)
sell starting at 50.00 and as much as 495.00!  Most are in the
437.00-495.00 range with some of the paperbacks going from 21-250.00!
WHAT?  So signed, this must be even better (especially since Zahi is a
very rare signer).  So maybe someone here can tell me, what makes this
book so special it gets nearly 500 bucks??????  More for signed?  

I got the information from Amazon, which is cheaper than say
Antiquarian book stores... so good deal?  I now don't feel bad about
spending 45.00.  I was excited to get the signature anway, even is
inscribed to someone else so guess that's all that counts anyway.  But
someone I hope can answer why so expensive!

PS here's the Amazon link:

http://www.amazon.com/Pyramids-Temples-Gizeh-Flinders-Petrie/dp/1854170511