...are the so pricey/expensive because:

A) They are very high quality knives/bayonets (cost of labor/materials).
B) They aren't really all that high quality, just hard to come by for civilians (supply/demand).
C) Other

I hope it's A since I just bought one...

As a knife, compared to others, such as some Tanto's, and custom knives.....they're really not that expensive.

As a knife designed to plunge through a ribcage, and repeatedly bayonetting someone......its well designed for that pupose.

As a general utitlity knife, to cut up meat, or small game.......no, you're better off using a butcher, or knife designed to cut.

Original Phrobis/Buck M9's are by far, the best made M9's.......anything else, is just that.....cheap copies, made by the lowest bidder.