I've got enough knives that I could stop buying right now and I would be pretty well set. I've just gotten a new Spyderco PM2 to try for EDC but I'm still looking for a new Benchmade to add to my EDC list. So my "last knife" would have to be a Benchmade such as the 890 or 913.
I've been collecting knives for a long time, and around 15 years ago I was buying a lot of knives. I got most of my wants satisfied so for some reason I moved away from buying knives and just carried various knives out of what I had. And then recently I got back into looking at available knives and wanting to buy more. I think a person can be satisfied for some amount of time with what they have, but as the market continues to produce more designs there will eventually be a time when you will want to buy more. If someone handed me the Benchmade that I am looking for I could say I'm through buying for now, but there would be other odds and ends that I would still like to buy for whatever reason.