Good catch, LostGeneration!
So, the subject of quote is about books, not scrolls!
"Reading and Writing in the Time of Jesus," Chapter 6, "Who Read and Who Wrote," page 165:
"It is very difficult to estimate the price of a book, but if a roll of Isaiah, a long one (see Chapter 1, p. 26), took two to three days to complete, then a little over three days' wages might be an appropriate figure, plus the cost of the roll.
… and that may be an exemplary rather than a real figure, and we may suppose a scribe might expect a slightly higher rate, we can guess at a price of six to ten denarii for a copy of Isaiah. While that is not cheap, it would not put books out of the reach of the reasonably well-to-do."
No wonder the esteemed Watchtower scholars chose this author, note how he writes: but if, might be, may be, we may suppose, might expect, we can guess.
Prof. Millard's distinction between scrolls and earliest Christian books is further fleshed out in an interview here.
THE TURNING: Now, we talked about earlier that people were writing things down on waxen tablets as well as if something really mattered, they put it down on scrolls, but of course the Christian tradition has Bibles. It has books. How did that transition happen? Why didn’t we have a bunch of scrolls?
MILLARD: It seems the book with pages was beginning to be used in the 1st century. There’s a Roman writer called Marshall, who says to his friends, this idea of having books written on pages rather than scrolls is very convenient if you’re traveling; it’s easier to use such a book. It’s also more economical because scrolls were usually only written on one side whereas with a book, you use both sides of the page. This sort of book seems to been used for possibly technical handbooks in the 1st century. And in the 2nd century, there are just a few examples from Egypt of Greek literature written in this form and they are mostly legal texts and things like that. It’s possible that it is a form of book that’s more common in Rome than in Egypt in the 1st and 2nd centuries, but we simply don’t have any examples from Rome. The ones found in Egypt might be written outside the country. It’s impossible to tell and I think the Christians thought this was a very convenient, economical form of book. They may also thought that it was less likely to draw attention to itself than a scroll in situations where Christianity, being the illegal religion, owners of Christian books might well be persecuted.
THE TURNING: So it’s sort of the original pocketbook, in a sense?
MILLARD: Yes.
Again, note how he speaks:
It seems, seems to be, possibly, it's possible, might be.
It's impossible to tell, may also, might well.
~Sue