the only way to get it that low is to have the $100 New Every 2 (NE2) credit applied to it.
if you are a non primary on the family plan, technically you are not entitled to a NE2 credit at all, only the primary is. but depending on who you talk to at vzw, they can let you "steal" the credit (i'd ask the primary if it's okay first though)
so technically, for you if you went to the website once you account was eligible for upgrade, it would cost you 199+tax
the NE2 credits have generally also been lowered (for newer plans i think) to $50 instead of $100 too.