So I was watching this documentary on the history of the Calculus, and this fellow was reading from Liebniz' and Newton's respective notebooks, and I was noticing the impossibly small size of their script relative to my ponderously wasteful use of scratch paper. This got me to wondering what the cost of paper would have been back then, and also what folks would have used to work out their problems as they went. Chalkboards?
Thanks.
In the incunable age, i.e. from the inventing of the printing press to ca. 1500, a book printed on paper without a binding sold (in Venice) for a price approximately equivalent to the daily salary of a skilled laborer, so say $100-200 modern dollars. Napkin math: 300 page text gives us somewhere between 20 to 75 sheets of paper (depending of how it was folded, octo to bifilium). Let's say the price is for a quarto, so each sheet becomes 4 leaves or 8 pages, which means we need 38 (large) pieces of paper to make our book. Splitting the difference on the price gives about $150 for the book, and if we guesstimate 20% of that is from materials, that gives us $30 modern dollars for those 38 pages, or just under $0.80 a sheet.
This is pretty cheap, and substantially cheaper than parchment. It gives us a useful baseline to talk about the cost of material and labor, but we must also realize there was a wide range of prices for materials across time and space. Paper costs mostly depended on the prevalence of linen clothing. Tree-fiber paper would wait until the 19th century. Before this, paper was made from linen rags, and thus the cost of paper were tied to their availability. If you lived somewhere where people wore a lot of wool, you'd probably pay more for paper.
However, for both parchment and paper, the cost of materials was not usually a factor that dictated script size. Despite the high cost of vellum, medieval manuscripts had very wide margins (though they are often now found trimmed). Although helpful for note-taking, this was an aesthetic choice. Scribal abbreviations certainly shortened the overall length of a text, but they were designed to save the scribe's hand, not material cost. Even parchment manuscripts produced under the pescia system in medieval Paris - essentially medieval textbooks - do not show concern for wasted space, though they might use lesser quality materials.
Basically, if you knew how to write, you were almost certainly wealthy enough that the cost of materials was not a particular problem.
For scratch, sometimes people used the margins of books, sometimes they used chalk, and sometimes they used wax spread over wood.