Upgrading from monoprice 8323

I currently have a pair of mono price 8323 which I love, but would like to upgrade. They are just to uncomfortable to use  for a long period of time. I have a budget of around 150 but would possibly extend it a little. I mostly listen to all forms of rock, dubstep, and soundtracks from games and movies. I have had my eye on the sennheiser HD 439 as they are only 45 bucks for a refurb. I will mainly be using these for the bus ride to school and for gaming. They need to be closed also. A removable cord would be nice, but not needed. I won't be buying for a while.

Sorry for any errors, I'm typing on a tablet.

Audio-Technica ATH-M50 are right up your alley.

Sennheiser 558s or 598s, depending on where you buy them, should be right within your budget. Both have fantastic sound quality :)

I would go for the 558s, but they are open. My friend has a pair of m50s and I've tried them and I don't really like them. I think they're overrated within the audiophile community.

Edit: I don't mind buying used/refurbs. 

Does anybody have any other suggestions?

the only closed headphones I could ever suggest are the m50s, I favor open designs. IEMs however, I thoroughly enjoy my Shure 215s, best IEMs I've heard in my life. I've heard good things about the HD280s from Sennheiser, On sale on Amazon right now actually.

I've been checking out the beyerdynamic dt 770 80 ohm. Would they fit my needs well? 

Yeah, but I don't know about quality of those. I have no experience with Beyer-dynamic, and I personally don't like them for lack of really good build quality, not enough metal in the frame design for me.

Really? Almost everything I've read on the internet has said that they are built like tanks. I've also heard people say they're built better than the m50's. Do you think just getting a pair of hd 439's right now would be a worthy upgrade over my current setup for now? (Forgot to mention earlier that I have a Fiio e6)