Hi Magnus,

You might also want to take a closer look at the following:
AKG K712 - a marked improvement over the previous model (702) and with a sound signature that should suit your requirements. You can find them at substantially discounted prices on the internet.
Sennheiser HD700: as above.
HiFiMan 400i: One of the cheapest planar headphones available and at a bargain price; great value for money, decent build quality and very comfortable too.
Audeze el8: A tad over your stated budget but certainly worth considering. Their sound quality is hard to beat. Perhaps a look at the second hand market?
Beyerdynamic T90: Owned these for a while; build quality is sublime (far better than any of the above), very comfortable and do most things very well. Good all-rounders but I personally found their midband to be a little on the cold/clinical/analytical side of things which is the reason I sold them. YMMV though.
Hope this helps
Best
-j.