-Delica 4, FRN, VG-10 blade: I would say the standard for a $50 EDC knife.
-Byrd Cara Cara G10: uses 8Cr13MoV, which is like chinese AUS-8. For $30 or so, these are very solid knifes with great attention to detail. I actually like the way it fits my hand better than an Endura, but the quality obviously isn't the same.
-Spyderco Tenacious: G10 handles, linerlock, full flat-ground leaf shaped blade in that same 8Cr13MoV. Spyderco's low-end model is still very well built. I traded mine for a G-10 Byrd Crossbill, but just because I wanted a Hawkbill blade.
-Kershaw Skyline: the perfect small EDC. G10 handles, single liner, 13c26 blade, tip up or down right handed clip, flipper and ambi thumbstuds. This knife is right about 2oz, has a very useful blade, and is just very satisfying to hold - an extremely well-designed knife.
-Kershaw Leek, framelock - assisted opener, framelock, 13c26 (or now 14c26n, i guess) steel, great ergos, very slim profile is good for dress pants, tip up or down right hander.
-Kershaw Lahar: a bit above $50, but a great knife. Thick liner lock, VG-10 steel, G10 handles, very solid.
-Kershaw Shallot: Like a bigger leek, but with a recurve blade. VERY fast opening, not sheeple friendly in the least (especially if it's the black model)
-Benchmade Griptilian/Mini Griptilian: axis lock, 154cm steel, poly handles, basically what many people consider the standard of EDC knives. I like the Delica better but this is a great knife.
-Kershaw Mini-Cyclone: aluminum handles, 13c26 steel, assisted open with an on/off switch (which is nice), fantastic design, very solid knife, very "cool" if that's your thing. I love mine.
-Kershaw Junkyard Dog II: the smoothest flipper folder I own. Kinda big. G10 handles, big liner lock (some models like the SG2 have a framelock in certain versions, it gets confusing with limited production Kershaws, honestly)
-Kershaw Groove: My favorite EDC knife, usually fighting for the honor with my ZDP Delica 4 and Kershaw Skyline. RJ martin designed manual flipper, framelock with G-10 overlays, SO smooth, has those nifty RJ Martin striations in the blade. Can't say enough good things about this one.
and what i'm getting myself next, I think it will make a great EDC:
-Kershaw Zing, Kershaw's second production version of an RJ martin design. same cool striated blade pattern as the Zing, a bit smaller, with thumbstuds and a flipper. textured poly handle. new 14c28 steel, too.
the good news is there are SO many choices for a great <$50 EDC knife. The worst part is picking ONE.