I'm going to echo and amplify what Antdog said.
There is a point of diminishing returns, somewhere around $180. Quality improves until you get there, and it seems to be at about every $20 "step".
300 dollars is going to get you into the used market for some mid-tech designs, but if you're buying new, you're not going to see the same kind of value for the dollar improvement that you got up to this point.
Lately, my choices for everyday have been (mostly) way below $300, or even $180.
My Alox Electrician goes with me to work, every day. Sometimes I forget, and leave it in my pocket on the weekends.
My copper Ripple gets pocket time when I want something light and easy to carry.
If I think I will be in a non-knife-friendly environment, the Skeletool CX goes in the pocket.
My Kizer/Gingrich Gti gets a lot of pocket time: fine, sharp instrument, with excellent ergonomics.
CRKT Batum. Chunky goodness.
Finally, this $11 slipjoint. Does everything a knife "needs" to do, and is actually a rather brilliant case-study in value engineering.
The Gti was the most expensive, at $140, because I had to have it. Next is the Skeletool, which can be had for about $80.
The point (besides posting pictures), is that there is a brilliant variety to be had, no matter what you want to spend. People buy knives for all sorts of different reasons, so you should be honest with yourself about why you're purchasing the next one.