I found this Stanley utility knife, which I was a bit surprised, didn't already have. So that was a good find. This one is very well made.
And I came across this one, which now officially is the cheapest utility knife I have ever had the misfortune to have seen and bought. Everything is plastic except for the worst blade locking mechanism I have ever seen, and the clip.
The blade guard is cheap plastic. In fact, one of the blade guards plastic ribs is cut right through. The liner lock isn't very functional, and down right dangerous as it sort of refuses to lock unless you reef the blade as open as you can...and it will just engage with some authority. The blade retention mechanism is a very bad design necessitating one to unscrew the bolt almost completely off...and I can tell you with experience it is a bear to get back in properly if you ever go to far...which is all too easy as you almost have to in order to pull the blade out. Yeah, this one is a real winner.