I found a similar thread that gave an old URL that still works.
http://www.amazon.com/gp/product/sitb-next/0060530626/ref=sbx_txt/002-2018152-0260852?_encoding=UTF8#textstats
I found that if you replace the product ID in the url you can still access the "text stats" page. I only tried it on two books but it worked on both so I thought I'd share.
In the above URL, replace the 0060530626
with the product id of the book your are looking for. To do this, find the book you want on amazon. Here's an example of one on amazon: www.amazon.com/How-Read-Book-Intelligent-Touchstone/dp/0671212095/ref=sr_1_1?ie=UTF8&qid=1417307816&sr=8-1
The ID here is the number after /dp/
. So if I replace the id in the first url with the id of the book I want, I can see the word count of that book! :)
http://www.amazon.com/gp/product/sitb-next/0671212095/ref=sbx_txt/002-2018152-0260852?_encoding=UTF8#textstats
Not sure how long this trick will work, but someone might find it useful.