I highly recommend the HD600 from headphone.com. They are indeed a tad higher than your budget but by very little, and I guarantee you that they have accuracy, smoothness, and dead-on neutrality that beats the DT770 which I know you listened to and I heartily did too for a long time.
In comparision, the DT770 sounds hollow, colored, and way too wispy and airy in the high end.
The HD600 sounds better by a good distance even out of low-end amplification like my airhead so you don't need to buy an amp if you already have one. However, the sound is just freakin incredible if you match them with a nice solid-state amp.
Trust me on this one. Go 600s. I've heard the CD3ks and they slightly alter the tone in comparision to a live performance or the HD600s due to their closed nature. However the CD3ks do stick the details in your face, whereas the HD600s stick them where they should be: At the instrument and balanced on a logical soundstage.
Audition both of them; you may disagree and enjoy the 3ks. However I find the 600 a better headphone.
Cheers,
Geek