Question: What criteria do you use to establish whether or not a fountain pen is cheap/inexpensive?
Not speaking for anyone else:
A cheap fountain pen to me is a pen model of which it cost me A$30 or less to acquire a unit, and would cost me A$30 to replace. I don't care how sought after it is, what anyone else thinks of that make and model of pen, etc. If I manage to pick up a Platinum Balance in good nick for $25, it still wouldn't be a cheap pen to me because I don't think I can just buy another to replace it for $30 or less. On the other hand, the Monteverde Monza is a cheap pen, because it's always on offer for less than $30, even though one would argue that one could get almost exactly the same pen in a Jinhao 992 and spend much less to acquire it.
An expensive pen is one that cost (or would cost) me A$150 or more in item price alone to acquire. Most of the dozen or so Pilot Capless pens in my household would fall into that category, but there were some we bought at bargain prices (around A$90–$120 each) new. Anything that isn't an expensive pen, as the complement in set theory, is an inexpensive pen to me. If I lose one of those Pilot Capless pens that I bought for A$90 a long time ago, I'd say, "Oh well, that wasn't an expensive pen," even though there is almost no chance that I'd be able to replace it with a new one just by spending that amount of money.