I figure there are probably a few people here who are in the market for noise-cancelling headphones, so let me share this finding...
I got a pair for $20 at Walgreens. They're the Coby brand. You can find them in the gadget aisle. The only thing weird I've noticed is they produce a little bit of white noise. Other than that they do the trick. I keep a pair in my desk at work, and plug it into my MP3 player. Now my co-workers can yap all they want and it doesn't bother me. I still hear bits of conversations, but they're easier to ignore. Also, the other day I wore them in the server room (a room in which you may find the sound of literally dozens of cooling fans along with the system for cooling all the network gear... I work in I.T.) and it made a HUGE difference.
Anyway, I thought there might be a few here who would be interested in acquiring such a thing. Let me know what you think.
(FYI, it's after midnight where I am and I'm drunk off my ass. Pardon any incoherence in the message.)