Which headphones would you recommend for me?

get the new in open box d5000 or

 

HE-400

Neither of those would be a good choice for someone using their ipod or PC. I suggest putting $100-150 of the budget toward an amp/dac(something portable so that it can be used in both situations). What kind of music do you listen to op? Its hard to recommend you something without knowing your listening preferences or music taste.

A LOT of options for that budget. Denon AH-D2000, AH-D5000, Sennheiser HD 598, Ultrasone Pro 900 (take a good look at these), there's plenty of choices. 

 

Take your time to do research and find out what would suit you best. It might be overwhelming with the amount of choices, but absolutely do not give up and just get Beats. It would be a shame if you wasted such a budget on Beats.

Yep, what others said.

 

IPod use?

You might need a portable amp and maybe a desktop one (not necessary with the FiiO E7)

 

So the poster above me is already wrong with the Denons.. even though they are just beast <3

 

 

Tell us some music genres, portable/non portable use (even though it seems like both in your case, you got an amp/you have no amp.. 

Check the headphones on the ultrasone range. HFI-580's to start. 

Didn't like the AH-D2000s eh? *sadface*

Well, i would have recommended to get the Denons, along with a Fiio E10 or something like that. But, i digress. You should try them anyway, with an E10 (i find the D2000s to sound amazing with the E10) because after you get used to their relative neutrality, they sound amazing. And hey, if you get an E10, you can always just flip the bass-boost switch whenever you want more bass. Trust me, i understand the first impression of not liking them, they sound very... 'airy' and alot of people don't like that. but... ounce you get accustomed to them, they do a really good job with most everything, sans a few genres. They do, IMHO, sound *amazing* for electronica. And hey, if you don't like them, just return them, and keep looking! But always remember, never, ever, buy based on first impressions.

Alright, so judging by your prefered music genres and your opinion on the Denons you would probably like a headphone with a forward(not recessed like Denon) midrange and punchy bass(good for rock/electronic/pop).
I am in no way an expert on portable setups but from what I've read maybe a Sennhesier HD25
http://www.amazon.com/s?ie=UTF8&keywords=sennheiser%2025&rh=i%3Aaps%2Ck%3Asennheiser%2025&page=1
and a Fiio Dac/Amp would be right up your alley.

I'm going to have to disagree with the previous Ultrasone recommendations. Rock and pop music are usually mixed hot in the treble and more times than not brickwalled in production(look up loudness war if your not familiar with this) and Ultrasones play very poorly with such recordings. Anything with a sub-par master will be rendered harsh and painful to listen to. They sound like pure bliss with electronic music though.

Like the above poster said, a lot of people find the denons 'airy'. From my experience you get an airy sound with boosted treble. Airy sounding headphones are usually not a good choice for rock and pop music from my experience at least, the exception being upper end Grados or so I've heard.
Edited by MohawkUS - 2/7/12 at 4:56pm

I think they'd be a good choice then. Just make sure you put the rest of the budget into a good dac/amp, the PROs will not run straight off an ipod. When I had the PRO2900(same drivers, different housing) they were so underpowered on my Fuze that the vocals disappeared completely.
I'm not sure on what portable amp to recommend you, but Fiio has recently put out a lot of new stuff that is supposedly very good. You can check out some reviews here: http://www.headfonia.com/ or around here on head-fi.

E10 is  a great Dac/amp for home or laptop use, and there are several different mobile amps that are worth checking out. I would look at the Headroom Total Airhead. or, even better, get the headroom Total Bithead and you have a decent dac/amp for home, and a great portable amp. Just my ramblings.

Yes, the E10 is better than the E7, but not portable. Also, the Headroom Bithead is both a Dac/amp that can be used with batteries or on the go. The Airhead is only intended as a mobile amp. For you, i would recomend the Bithead, (http://www.headphone.com/headphone-amps/headroom-total-bithead.php) because its a good combo if you want to use it portably along with desktop use.