I'm not sure, but I suspect that, to some extent, the price may reflect the sophistication of the design and the technology in use.
For example, some years back, I recall that a colleague of mine had a .PDF file from a project management "cartel" trade association that he was a member of - the "Project Management Association", or something like that.
Anyway, he wanted to print out the .PDF document onto paper, but could not, because printing had been deliberately disabled in the security settings of the .PDF file. So he could only open it in a .PDF reader. Yet he wanted two copies - one for his desk at the office, and one for reference at home. I think the association took advantage (read "ripped off") members by charging them an arm and a leg to sell them a hardcopy of the document, and he wanted to avoid that.
The document was the then current year's members' handbook, containing all the arcane mumbo-jumbo methodology of the association that initiates had to learn. This was supposedly "proprietary" to the association, but was actually nothing more than the usual collection of project management theory and so-called "best" or good practice that is taught in business school and which has lain in the public domain since Taylor/Gantt.
I saw that he had access in his office to a software called Omnipage (I think it was that), so I suggested to him that the simplest thing might be to use Omnipage to open and read the document, because I had read that Omnipage could blindly scan a document image once it had it in RAM in video/screen output format, OCR it and output it to a .PDF or MS Word document file in a reasonable likeness of the original.
So he did that, and in one pass he easily outputted it to a Word document file, and printed off two hardcopies for himself and a third for me - for giving him the idea in the first place.
I looked through it and it seemed to be a very good likeness of the original .PDF file - images, diagrams, tables and all, and there were only a few minor OCR errors. You could always parse the Word document file with a spellchecker and clear up the OCR errors, and fiddle with any image oddities.
I do not know whether any copyright was breached in the process, but what did strike me (as someone interested in all aspects of desktop publishing) was the sheer sophistication of the software that enabled you to do all this. Omnipage was pretty expensive to buy.