I use Sony MDR-V6 headphones and find they have great bang for the buck. They have that reference audio sound which seems very clean, clinical, and present. I often feel like it exaggerates the sound of a mix so that if something doesn't fit, I can easily hear what element it is that's off.

The Sennheiser HD 201s seem pretty good for the money, but if you want the most accurate response, most even impedance, and best isolation, the HD 280s still significantly outperform them - especially when you look at low-end frequency response - there's nothing better to hear problem rumbles at low frequencies that you need to watch for when it comes to mic handling, or remove with high-pass filtering. I guess it depends on how serious you are, and how critical your ear is.

Thank you all for the advices. I have settled for Sennheiser HD201 for now, and I'm loving it so far. Very rarely I get a very slight weird "trebble" in the right ear from very few YouTube videos where the recording is of poor quality or compression. But, as I said, it happens very rarely, in fact I have not noticed it for the past few days. Overall, I'm pleased. While outside, you hear what you're supposed to hear - the signal from your recorder, although I;m still waiting for my shotgun mic to arrive. The sound quality is amazing. Sound isolation is pretty good, but not 100%. Very comfortable, I could wear them all day (be careful with those poor ear-drums, though) and the looks are very simple (so you don't look like a nerdy alien wearing them). For £15.99 + free shipping from Amazon - this is perfect for now. When I get a dedicated boom/sound man, I'll probably get authentic Sony MDR7506.

I use a Senheiser PX 200, the first version of this http://en-de.sennheiser.com/px-200-ii It's one of the best choices if you work the most part of the time traveling

The ones mentioned here sing, but here's a quick value list:

Lowest cost: KSC75 Modded - $15

Portapros Modded, EQ'd to reverse of Freq Response - $35

Grado SR60i - $80

HD25 - $200

The key with the low cost Koss is to recable them to get rid of the easy to break stock cord that constricts the sound, and maybe Kramer/quarter mod them + an in line resistor. Also, you will get vastly improved voice coil response by a slow burn in of your cans - low volume midtone classical for many hours, then increase volume a notch and repeat, until you reach high volume over the course of a couple days. Years ago, I did a test by breaking in one set slowly, and the other more quickly (loud). Though they were the same cans, the slow break-in set still sounds much richer, having put them both to use over the years.

;)

Check out 2:04 -

Also, can't stress enough the importance of

a) discreet sound card

b) linear eq

Here are the settings for grado 60: http://www.head-fi.org/t/575039/grado-sr60i-equalizer-settings

And plug in the reverse of this for the Porta Pros: http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=1613

The headphones will come alive; and here are quality sound cards for all budgets: http://www.newegg.com/Product/Product.aspx?Item=N82E16829132013 http://www.newegg.com/Product/Product.aspx?Item=N82E16829132014

Both of those have upgradeable op-amps to achieve incredible sound.

as it was mentioned often I bought the HD 201. I must say I am very disappointed. Isolation doesnt deserve the name, output level is so low that I could not use it for watching a movie on the iPad during a flight. Byuing cheap means buying twice :-(

I have DT 770 80ohm witch I love and use a lot. Then my wife started to use them and take them to work every day. So we had to find something else. Considering that she was already spoiled and wanted something good and comfortable :) we took these ones: http://www.amazon.co.uk/Panasonic-RP-HTX7AE-K-Retro-Monitor-Headphones/dp/B004UDTM1Q with little modification ( http://www.head-fi.org/t/449350/panasonic-rp-htx7-what-a-suprise ). IMHO best price performance on Amazon.

I'm a no-budget bastard looking for a decent pair of closed headphones for field monitoring with my h4n.
Here in my country I can get AKG-K44, Superlux HD661 (MDR7506 wannabes) or Takstar HD 2000 for similar price. (I've tried Senns 201/202 and I really didn't like them for monitoring) I was leaning to Superlux because I've tried and liked the brand (I have and love the 668B for inside use). They seemed to be a cheap alternative to the 7506 but I've seen some reviews talking about them being not that comfortable.
Regarding the Takstar, they're a bit cheaper than the other 2 but I've only found a couple of reviews, although all positive. Two sided cable :S
The AKG-K44 have been previously recommended here in the thread so I guess they're a safe bet, but seem to be the bulkiest of the 3.
Any updated insights about this? Thanks!

Thanks @Vitaliy_Kiselev
Those were actually on top of my list, but here they're 2 or 3 times the price of the three that I've mentioned, and sadly out of my budget :(

I don't want to sound stingy, but those are out of budget too. Here in my country you can only get the original ones for 150 bucks. And it's important to mention that we have lots or problems importing foreign products now, so that alternative (that I've used to consider) is almost impossible.
Beyer DT231 and 235 are also in the price range but I've read they're not that 'flat'.