Page 275 of Fraser and Schewe’s Image Sharpening book (about $40.00, if I remember) helped me greatly in making sure that my files would print perfectly on press, and helped me get a fairly good reputation with pre-press folks. I kept meaning to spend another $50 or so on Schewe’s later books but never go around to it. Maybe next time I will not wait!
Now, paying hundreds of dollars for a book, wether a collector’s item or not, is not my cup of tea. However, some people will pay as much or more for a weekend workshop in order to gain a bit of knowledge. So, perhaps a $1,000 Digital Negative workshop, and get a book free? :-)