The MS-1 is a good suggestion. As is the Grado SR-60. The problem with a lot of higher-end cans, like the Senn HD580, is that they'll need amplification. The $150 price tag of the HD580 doesn't include the $100 minimum price-tag of a non-DIY amp (amps can get really expensive really quick as you go up the ladder), and the cost of a good source, which can range from a good cheap soundcard (Chaintech AV-710) to CD players costing thousands. Simply put, this headphone is made for good gear. You can, of course, use it with anything, but you'll want to upgrade once you have a pair... and that's where all the extra costs come in.
The SR-60 sounds pretty good out of just about anything. As does the MS-1, though it's more selective. That's one main point in favor of these over something like the HD580, which is technically superior.
I'll throw in some more recommendations:
Audio-Technica ATH-A500 and A900 - very big, very comfy, good sounding, easy to drive, and closed/isolating. They're good starter cans.
Sony MDR-V6. This is not the V600! The V6 is a staple of studios worldwide, and for a good reason. It gives you pretty good sound, good isolation, good durability, all at a very reasonable price.
Beyerdynamic DT770. If you like rap, these will be great. Massive bass out of these suckers, but without sacrificing overall quality. They need an amp, but you can get by with a powerful headphone jack in your home receiver. If all you have is an ipod, then you'll need an amp for them. They're also closed, isolating, and very comfy.
Sennheiser HD595 - the 50 ohm version of these headphones can be driven fairly easily unamped, which is why I'd suggest these over the 580 if you're not planning to use an amp at all. They are very clear but warm and pleasant sounding.
And, if you're planning to go all the way, then yes, the HD580, together with a good amp (Portaphile V2 would be my choice) and a good sound card (E-MU 0404) would be a great rig that will last you for years. The 580's are the entry point into real hi-fi. But, if you're planning to go with these, get ready to spend a lot more than $150. The good news is that you don't have to lay it out all at once, and can assemble your rig piece by piece. The bad news is that the HD580's won't give you their best sound until you do.
[Edit: Oh yes, how could I forget... Welcome to head-fi, sorry about your wallet!
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