I use ggplot2 regularly and have read Wilkinson but honestly I have a bit of trouble seeing how ggplot2 is an implementation of Wilkinson's book.
(It's been a few years, maybe I should take another look at the book.)
(It's been a few years, maybe I should take another look at the book.)
> ggplot2 is a system for declaratively creating graphics, based on The Grammar of Graphics.
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.