I've had my pair of M4U1's for years. I love these to death. The stage is small, but these have a great, warm sound, isolate well (used these on more than a few plane rides) even without the ANC model, and are incredibly efficient. The plastic material does feel flimsy, but using the carrying case while traveling with it, mine are STILL going strong.
Edit to add: I paid $300 for mine, when they first came out. No regrets. Easily worth 130.