I can easily imagine people wanting spices and for the purposes benbreen (the OP) says, including as components of drugs (in the medieval sense of drugs as described).

But a key to spice trade puzzle, for me, is the transport cost. Some shipped almost all the way around Eurasia, the long way. I know sea transport was and is relatively very inexpensive, but how much did it cost in the technology of the time? And they also had the overhead of military costs. What was the total cost of procuring spices, if that can be calculated?

(Also, I'm not quite clear about the time period this history describes. Freedman's book's title says it's about the medieval period, but most examples in the article seem to be early modern. It's starting to sound like a wide swath of history.)