RCD510 can be had for around £350, but why not go the whole hog and get a RNS 510, and camera retro fitted for around £1000, or in stages,
£600 buys the latest RNS 510, and around £350 ish buys the rear camera. Both are very easy to fit, camera takes about 2hrs, or just about 80 mins if Steve and myself are on song.
RNS takes minutes. I
f you do decide to Retrofit an RCD 510, make sure it has a TV in port in the rear, not all do, you will need it should you decide to fit the rear camera.
Oh and go for the newer car.