For fixed blades I found the more you spend the more the it is worth it... I've seen the very opposite of the "diminishing returns" everyone assumes exist (for fixed blades at least)... My BK-9 was unusually good for a cheap knife, but its blade was slightly curved sideways from uncontrolled cooling warping after heating... It went in the trash after a few months, largely because of that, though this had no functional effect: I just dislike badly made things more and more over time...
My Randall Model 12 was eight times more expensive, is over twice as thin at the edge, tree times as sharp, hollow ground so twice as effective a chopper, and will last decades upon decades of hard use at the exact same sharpness, given the "edge wearing" room built-into the hollow grind cross-section... Oh and the Randall is much, much, MUCH easier to clean, doesn't rust at the edge or elsewhere, and has a more confortable handle. Which one do you think was a better deal?
Gaston