Cost to produce the Voynich manuscript

[Jorge_Stolfi]

I'd think the lowest cost possible is 0, they made all the materials and completed it themselves.

Vellum making (and leather making in general) is a laborious and smelly process that requires specialized tools, frames, know-how and and skills.  Not very fancy, but not trivial either; not things that a generic scholar or student would have.  No matter how poor the VMS Author was, it is far more likely that he bought, begged, or scavenged that vellum, than he made it himself.

People who used iron-gall ink usually made it themselves, because it would not keep for a long time.  They may collect oak galls in the woods, but the other main ingredient -- green vitriol -- was harvested from puddles inside old copper mines, and thus had to be bought.  (Although, as I have explained before, I believe that the VMS ink is not iron-gall but more like a watercolor.)

All the best, --stolfi