Yes, I do have a copy. I'll have to double check. I know I didn't pay $500 for it.
After checking, yes I did see the price on Amazon for just under $500. This is obviously someone who has a copy and wants to rip off someone else. The new list price for the book was $29.95
I did find one LFS that had it listed on their web site, but call first, because it looks like the book is in very short supply. Here is the link - (offsite) -
ESCOBAL* Aquatic Systems Engineering