"Papyrus Cheese" was a problem even in the original Baldur's Gate, where every group of gibberlings seemed to have one or two libraries. According to the AD&D DMG, scroll production is not a trivial thing, and certainly the value of a scroll should be high. The basic elements of scroll fabrication included the following:
1) Must be 7th level or higher to scribe, and of level high enough to cast the spell normally
2) Takes 1 day per spell level of preparation per scroll, and chance of success is not 100%
3) Requires special paper, but not too expensive
4) Requires special ink ... this is where it gets really interesting! A Protection from Petrification ink requires eye of basilisk, feather of cockatrice, and venom from a Medusa snake. And also some crushed peridot and topaz gems, and six pumpkin seeds.
I just don't think scrolls should ever be included in random treasure drops.
