They're out there, but they definitely aren't as common as the 444s, same goes for 460 vs 464. A few months ago I picked up a 460 really cheap because the housing was cracked. I repaired the crack to be near invisible and it's a very nice phone now.
However... All of the buttons were stuck down at once. The buttons are made of bakelite and the housing is plastic(obviously). What happened is the holes in the housing shrunk to the point they were tight on the buttons so the buttons would stick. The bakelite buttons have a small flange that captivates them in the housing, that's the part that was bound. I spun all of mine in the drill and carefully filed a little bit of that flange off, just enough they moved freely in the shrunken holes. In the event the buttons on your 440 are stuck, you might end up needing to do the same.
Eric