Kershaw, Spyderco, Camillus, Wenger, Victorinox, Kabar, and SOG all make really good knives at the price level you're considering. You can also find a few Benchmades such as the Griptillian/Mini-Grip for that money. My personal favorites right now are Kershaw and Spyderco - I carry a Kershaw Storm II (30 bucks...had it for four years now), a Spyderco Native in VG-10 (40 bucks...stay away from the SV30 version of this. Chips too easily), and a Becker BK-11 Necker w/Mini-TechLok (this also cost me about 30 bucks).
Gerber used to be a good knifemaker but their quality has gone to crap. Buck also, IMO, is nearly the same story. Some of their knives, like the 110 are still awesome but most of the new stuff just plain sucks.
Wanna hear my suggestion on this? First, check out
http://bladefroums.com and look around. Reviews abound as do opinions on knives (along with a bit of good ol' brand-whoring...overlook that part

) and you'll soon have LOADS of useful information floating around in your head. Secondly go to Walmart and check out their better knives. You may also consider a hunting/camping store...hell, anywhere that has knives setup so you can see and handle them before buying. Third, unless you can get a good deal in a store or like to patronize a particular brick'n'mortar store, online is the way to go. I prefer
http://newgraham.com as they're only located 2 hours away and have great prices. Other sites to buy from include
http://1sks.com and
http://eknifeworks.com