I came across a pair of brand new Arundel Mandible carbon cages for $78./shipped.
That deal I got by a member here on BF who heard of the deal.

Cruise the online bike sellers.
I got mine from WesternBikeWorks.
Art'sCyclery also has some good deals.
CompetitiveCyclist had 2 Mandible w/bottles for $100. once.

Best advice I could give is to keep an eye open.
These deals pop up quick just to bring traffic to the online shop's site.

Good luck.