I recently got an RCD510, with unlock code and FAKRA adapter for £150. It's the best mod I've done to the car so far, I love it
I did require a canbus from Eddie_NL, for my 56 plate car.
It cost £75, and came the next day.
Works perfectly, and I'd seriously reccomend an RCD510.. Although the RNS looks even better if it's in your budget