'Worth the cost' is surely immaterial. It's the only thing that matches. It's the only dock offered for the Air.
For better or for worse you're now in the Apple ecosystem. You have your non-options, and you pay for it, pure and simple. I don't mean that in any particularly weird way, it's just the way it is. I kind of don't get the people who buy a Mac and then try and twist other unsuited solutions to it in order to save a few bucks here and there. That defeats the object of the exercise.
I'm not the world's greatest Mac-lover, I honestly think the hardware is overdesigned junk and indicative of what happens when you let a team of prima donna industrial designers and a bunch of marketing guys who know uninformed consumers like the back of their hand run amok - but everything around my Macs are, as much as is possible, from the Apple ecosystem for the least hassle.