I thought the same thing, but for some reason it is separate.I think it may be kind of a "package deal" where everything needed is included.
I guess it is along the same line as buying the homelink mirror, and then having to buy the installation kit for it. I'm thinking it would probably not work unless you wired some sort of switch with the existing wiring that the turn signal stalk switch would use. Definitely not worth it when the stalk is only $46.It's not exactly cheap, but I picked it up for $215 for the fog kit (bulbs included), and $46 for the new turn signal stalk.
Excellent write-up by the way