I started this post earlier in the morning, so some of the points may already have been covered, but here you go..
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I'm not sure what the conversion rate works out to, but the DT880's are the best BeyerDynamics has -- which probably breaks your budget by a little bit. I think BeyerDynamics next level down would be the DT770's. They can be had for $200 online here in the US.
The equivalent from Sennheiser is the HD650's. Those usually run a little bit more, around $300 online. They're supposed to have a good low end. The 600's used to be their top of the line headphone, so that would be a good alternative -- they run ~$250 online. If that's still too much, then the 595's (I think) are the next level down. Those can be had for ~$160.
Then there are the AKG701's. These were my present to myself for surviving tax season. I have to admit that I haven't heard the DT880's, but I did like the 701's better than the 650's. Overall, they're great. They're not going to block out much noise, and they leak (just like all of the above), but man they sure are sweet. These can be had for $300 online as well.
Also, I second taking a look over at head-fi.org. There are a LOT of people that frequent that forum that know a LOT more than I do. And fanatical can be an understatement. I went to one of their local get togethers (I wanted to try out some headphone amps). Everyone was really nice, and there was a lot of cool equipment. Including a one of these:
Retail price: $15,000
Were they good? Of course. Were they $15,000 good? Can't say that I thought so. They were sexy as sexy gets though.. well, in electronics.
Another resource I'd take a look at is headphone.com. It's an online store that just sells headphones and headphone related paraphanalia., They've got some excellent writeups on most of the headphones out there. If you were located in the US, I'd even suggest sending them an e-mail -- they've got great pre and post purchase support.
Note: for those in the US, I think it was worth the extra few $$ to buy from these guys just because they do have great customer support.
To sum up -- if you can, I'd try to get the DT880's if you can get a break on BeyerDynamics. If those are above your budget, then the DT770's would be my next suggestion. That being said, I'd take a look at the offerings of Senneheiser and AKG as well as visiting head-fi.org and headphone.com. This all assumes that you're getting the best sounding cans as opposed to getting some that isolate you from the world. If you want a closed (blocks out noise and prevents leakage) set of cans, then we have to start all over
Oh, and all prices above are in US dollars.
JCD