if you are serious about your tacticality and your fighting, then you'll pay more for a knife. none of the truly serious tactical fighters I know ever carry anything that cost less than six hundred dollars, and that's when they're slumming it.
what is a tactical fighter?
None of the dea, swat, tac/crash squad guys I trained with carried anything more expensive than a spyderco folder. A few of them were former special forces guys. A couple do carry ~225$ smallfixed blades though.
A few of the FMA guys I knew carried 'nice' knives of varying price, but they weren't LEOs. They had day jobs or were instructors so fighting for a living wasn't really an issue.
If you really care about your self defense/offense, you'll use what works and it doesn't have to be that expensive. Your skills/ability on the other hand make more of a difference.