I've got pictures of three Cosworx wigs right now. ^^
First, an Ivy in Dark Blue that I bought for Konata from Lucky Star:
http://images.cosplay.com/showphoto.php?photo=1368993
A Wisp in the Violet/Grey mix for Tsukasa from Lucky Star:
http://images.cosplay.com/showphoto.php?photo=1368994
and a Punky in Silver White:
http://images.cosplay.com/showphoto.php?photo=1368995
I really like the violet/grey mix because it looks much more..natural, I guess, on my roommate. She's really pale and just the violet would've looked really harsh on her.
As far as Ivy goes, if you're tall and looking at this wig for a character with long hair, keep in mind that I'm only 5'2''. As you can see in the picture, it comes to about the small of my back.