Roman Aristocrats in Barbarian Gaul

In 1993, R W Mathisen, currently Professor of History at the University of Illinois, wrote

There seems to be an increasing availability of hard-to-find books, due to the fact that print-on-demand has now become more common. I used to feel rather smug about having tracked down a copy of Cheeseman's Roman Auxilia, but colleagues have remarked that these days it is much more available.

Just today I was buying for a copy of Hornblower's commentary on Thucydides, and the bookseller said that it would take an extra ten days because he had to print it. (It still cost $97, but at least because ancient history is my job as well as my hobby I can claim tax relief on it.)

Now I just need to track down Annotations on the Institutes of Gaius ...