I think your ranking idea is off for a couple reasons. You can have good knives that are pretty cheap, and you can have bad/mediocre knives that are pretty expensive. In my opinion, the term "budget" is somewhat subjective. Someone who considers buying a $125 knife to be the very limit of their comfort zone versus someone who doesn't have a problem spending $600 on a knife are going to have different ideas of what their "budget" knife is. And obviously, as a person's tastes and ideas about cost/value change, so will their definition of budget.
As far as the average use of the term that I've observed on these forums, people generally are referring to knives that can be had (not necessarily msrp) for below $60-$70.
At the same time, there can be qualifiers to the term. A lot of people might call the Spyderco Sage 2 or Bradley Alias budget Sebenzas.
For me, at this stage in my evolving knife-loving mentality, I'm pretty much focused entirely on CRK's, to the point where I am going to sell off a lot of my Spyderco's and other brands. At the same time, I decided I wanted a "cheaper" knife to take into situations where I might lose one of my CRK's (not because I don't use my them, I definitely do), so I've purchased a couple of the more straight-forward looking Emersons (A-100 & Mini A-100) as "budget" knives that are similar to my beloved Sebenzas in many ways. But even though this is how I mentally term them, I think if I was using the word "budget" to describe a knife on these forums, I would do so trying to keep in mind how most others would define the word.
