As I noted awhile back recently my EDC Cold Steel folder was a field loss of sorts. I didn't lose it but it is gone. Anyway I think that is a good reminder of a point about knives. Don't buy one that is so expensive it will be a real loss if it is lost/ broken/ stolen/ whatever. I hesitate to say an exact dollar figure that everyone should use because it depends so much on your situation. Being able to readily replace a lost knife is probably a good test. For me that is somewhere in the $50-65 range. For other folks it might be more like $25 or 400.
Like any tool you carry and use sometimes knives are casualties of some kind of event. The same could be said about a lot of other stuff including guns. Another benefit of carrying affordable knives is that you can, if so inclined, just keep a couple spares lying around in a box somewhere. Getting a couple of the folder I like to carry every day as backups is on my long list. A lifetime of outdoors activities has left me with a decent collection of random knives and a recent Cold Steel purchase gave us some intentional redundancy. It would however be nice to have spares of the exact knife I like to carry in my pocket. Maybe next year.
Anyway before getting sucked into the coolest new $342 tactical urban ninja SPECOPS elite fighting knife you really should think twice. Affordable knives have the benefit that it isn't a huge hit if they are lost or damages. Also it is a lot easier to keep a few extras around which never hurts.