I have several editions of the Machinery's Handbook in both print and PDF format. In total I have 15 printed editions from 1 to 26. There are another half a dozen in PDF format up to edition 29. I have the ones I use most often in both formats. I like the fact that I can look up a formula, dimension, or profile in the printed edition then print off a copy of the page from the PDF version. It saves wear and tear on the printed ones.
Like others much of the repair and fabrication I do is on older equipment. Some pieces date back to the early 20th century and use now obsolete thread fastener sizes, and tapers. If you visit e bay there always seem to be a number of editions available in both the printed and electronic format. The key is to be patient. Some sellers ask outrageous prices for books that are so badly worn and deteriorated they wouldn't even books make good scrap paper. Others are selling like new for a song. The most I've paid is #80.00 for a new book from a book store. Most used books in like new condition go for between $25.00 and $40.00.
Today when I searched "Machinery's Handbook" on eBay there were over 400 offerings. I'm sure some are pocket manuals or other offerings, but there are certainly a wide number to choose from.