I have the book! I just should figure out where it is on my shelves.

Rather expensive by my standards these days. When I was a starving student, I would not have hesitated to buy it from that corner in the back of Cody's Books.

Springer runs occasional sales up to 40% discount about once a year, but a don't recall if "The Grammar of Graphics" was eligible last time.

They're running a sale right now, through June 30, but it doesn't look like G of G is eligible: https://link.springer.com/shop/springer/yellow-sale/en-eu/