Why not buy one decent pen “shell” and then just buy the plastic tube with the tip and the ink afterwards?
I know many companies use pens for marketing but still, they could apply this too and also stand up for the environment while still do marketing.
There’s a type of Japanese felt tip which writes somewhere between a fountain pen and a ballpoint, and there are versions that can be filled with ink. They don’t need all the faffing around of fountain pens, and don’t dent the paper like a ballpoint.