i don't consider "headphones" to include earbuds, but I'd estimate the best earbuds for the money are probably the Shure E3Cs (unless you can swing the E5Cs).
Headphones are a different ballgame.
I personally like the Sennheiser PX100 for compact and affordable travel headphones. I got my Bose On-Ear headphones on ebay for less than retail, but any bose product is going to be about 2x more expensive than it should be. The OEs are really nice though, I highly recommend (especially over the regular triports which sound weaker to me).
There's also countless bulky studio style headphones, but if you're considering traveling around with your music at all, they're not too practical.
What I've found is you typically like the headphones you buy, regardless of their quality, as long as you're happy with the money you've spent. So they're all good!
:kissforeh