The DLC isn't really worth the asking price ... barely better than the horse armor provided in Oblivion.
I don't know how anyone can credibly make that claim, because frankly it just isn't true.
Even the leanest F3 DLC - Operation Anchorage - contains a good 2-4 hours of quest content, unique loot and a hefty expansion of the Fallout lore, and every DLC since has been quite bit bigger and a lot longer. Broken Steel reopens the game world after the ending, takes the story further, populates the landscape with new sidequests and NPCs (as well as the 3 big story missions, which are quite reasonable in length).
Whether they're worth the money is up to you, of course, but personally each one was 800msp well spent with no regrets. Either way, Horse Armour just isn't a fair comparison by any stretch of the imagination.