When I'm setting aside money for a new outdoor purchase, I typically won't spend more than $200 on a knife, because once I pass that threshold I'll just save a bit longer and buy a gun instead.
I consider a $100 knife expensive, and I will use any of them if need be; but I usually EDC knives that are less expensive, because my experience is that the minute I pack one of the expensive knives I'll find myself in a situation where I need a tool but only have a knife that wasn't designed for what I'm about to use it for... prying, unscrewing, etc..
This is where carrying an additional multi-tool pays off, but I don't always do that, because I like to travel light some days.
When I go out hiking, hunting, fishing, or camping, though, I will pack a couple of the more expensive ones that are less likely to let me down when I really need them... think Aron Ralston and 127 Hours/Between A Rock And A Hard Place.
Sometimes, when I find a more expensive knife that I'd like to carry but also worry about losing, getting stolen, being discontinued, or damaging, I'll buy 2 of them if I find a good enough deal... I actually have 3 of some knives.