K701 needs careful pairing with the amp departement. Personally I wouldn't follow that route.
HD598 is a good alternative for classical although it is the weaker overall sound quality offer on your listing.
MS1000 would be a good project to follow.
Can you pull AD900 (non-X)? This would be my first choice on a limited budet, but I don't really want to confuse you with more noise.
edit: I'm not really sure how much these go used. Just had a look on ebay and new they are not in your budget.
Edited by xaval - 5/19/13 at 8:49am