Affordable DAC for iPhone 5?

So I have a nice audio system ARC preamp, McCormack Amp, Martin Logan speakers. I just want to be able to play some music that I have on my iPhone 5.

Ideally I would like something that had a dock type setup - sit the phone on the cradle and has RCA output on the back. Simple.

Any suggestions? Prefer to spend $200 or LESS!

Thanks much.

- Rob