Thanks to the wonder that is toe-up socks, I found out how far a ball of Cherry Tree Hill sock yarn will go:
Up to my knees! Now, I have teeeeeny feet (size 5), and I'm 5'2". So, it might not make knee-highs for everyone.
Pattern: Knitty's Universal Toe-Up Sock
Yarn: Cherry Tree Hill (I think Country Garden, but the ball band is at home & I am not)
Needles: Bryspun DPNs size 2