Yet, Parabellum is WIDELY used and manufactured by the droves...so why aren't they milking that for all it's worth?
I'm no marketing guru but, maybe that's just it. The 9mm, as you said, has been manufactured by the droves for a long, long, time, whereas the newer .380s (Ruger, Kel-Tec, et al) have clearly been marketed to a new generation of people interested in SD. In spite of the fact that the .380 has been around so long (so, why all the hoopla?), the Emperor has got some new clothes (the newer .380's marketing), and everyone and their brother wants one.
Comparatively speaking, when was the last "new thing/development" for 9mm firearms that was anything like the plethora of .380 pocket pistols hitting the market? It follows that, since the .380 handguns are so much more popular these days, the price of the ammo can be set at the level of popularity (in spite of being a lighter bullet, smaller casing, and less powder). Essentially, you're not paying for the raw material, you're paying for the popularity of the round ...manufactures will charge what the market will bear.