My budget oscillates based on my recent spending and current account balance. Depending on how I'm feeling about cash on any given day of the week, I might say a budget knife is $40 or I might say a budget knife is $150... These days, I'm leaning towards the latter.
In fixed blades, though, as there are no moving parts, it's all form and steel. $150 covers an incredible range of quality and value in the fixed blade world. I picked up a 3V Master Tanto for $160 shipped, which I would call an incredible value for what I got. I also paid $23 for a CRKT Dragon which I also carry and use quite a bit.
With folders, it's all over the place as well. Some days it's a Kershaw Launch 6, some days it's a Boker Plus peanut, some days it's a Rough Rider. Anywhere from $8-$200, with the decision based more on what I'm doing that day than anything else.