I sold the last print copy of Modern IDL that I had this morning. At this time, I do not intend to make another print run; the PDF will be the only version of the book from now on[1].
While I continually update Modern IDL for new versions of IDL, only the PDF purchasers get the full benefit of the updates. The hardcopy version was often a version of two behind because of the way that I placed orders to my printer. PDF purchasers also got future updates[2], which was, of course, impossible for the hardcopy version.
For those who still really want a hardcopy version, you have permission to print your PDF. While higher, I think the total cost of the PDF plus printing/binding at Kinkos shouldn’t be too much more than I was charging for the hardcopy.
Although, I don’t have anything against other electronic formats. If you have a favorite electronic format that you would like to see Modern IDL available in, please let me know. ??
PDF purchasers will receive updates until IDL 9.0, when you will have to purchase again to receive further updates. ??