I use and abuse Radio Shack Pro 35s, as suggested earlier in this thread. They're heartily build phones that take a beating, and another, and another, and another, and then when they do die, they're inevitably on sale. I have never paid more than $20 for these cans. I just last night took off the worn out foamies and replaced them with a $2 set of foamies out of the machine at work (I work at a call center...)
I have a pair of Shure E2Cs that I liked at first, but I like less now. Maybe I'm not wearing them correct, or maybe I just have small ears, but they're just not all that comfortable. I could try to sell them, but there doesn't seem to be a huge market for used, in-ear buds, even if you include replacement plugs et. all.
I want a pair of Grado SR-60s next. If, for nothing else, to answer the question for everybody on the web as to weather they are better than the Radio Shack cans.