I bought a pumpkin unit off Amazon, I cant remember which one it is off the top of my head but it was about £200, I decided to cap my budget at £300 and the facia and Connects2 were about £100 if I remember.
Most of the £200 android head units seem alright; I run up a hotspot on phone when I want to use google maps to navigate, the bluetooth calling and audio works well and being able to playback music from a USB stick is great. I guess you can run up any android apps you might want as well, but I've not seen the need. Mine has support for reversing cameras but I didn't bother fitting one.
Whilst the fitting kit seems a little expensive it dose work very well, you can use the steering controls and you still retain your date/time and AC display. The display is controlled by the OEM headunit so an adaptor is necessary unless you want it to be blank.