I've owned a few sets of in-ear headphones in the past from various manufacturers (2 pairs of Sennheiser CX300s, some JVC and some Panasonics which, like a fool, all cost me between £25-£40). These are by far the best in-ear headphones I have used and I would be surprised if you could get any better under £50.
Surprisingly deep bass, after reverting to the standard iPod headphones whilst waiting for these to arrive, it was such a treat to stick these in. Nicely crisp and clear sounding, barely leak any sound and block outside noise fairly well. The sound quality is amazingly good for the money. They seem a lot more solidly built than the CX300s for instance and I have had no problems with them falling out.
For the price - this is an absolute steal!