I’ve carried and used some fairly expensive knives - A sebenza insigno w/CF inlays, a 0560CBCF limited edition, a gold-class mini barrage (red c-tek), and a few others that slip my mind.
I never really held on to them, though, because as novel as it was, it felt like I was carrying a bejeweled hammer around to occasionally hit a nail or two.
The most expensive knife I carry and use frequently is a Spyderco Caribbean, which feels every bit as nice as any $300-$1000 knife I’ve handled and likely has the best cutting geometry of any of them.