Recommended sat nav system?

Hi all,

Sorry I've been trawling through quite a lot of these same kind of questions but would just like to confirm with others more clued up than me that i am buying the right thing before i part with the cash.
Im just after standard RNS unit for my 2007 S3 with Bose, I gather the RNS-E is the one to go for? Also where is the best place for a double Din cage to suit.

This seems best deal i can see what do you think:

RNS-E AUDI A3, S3 Navigation LED MEDIA CHROME. SATNAV, DVD 2013 MAP ... | eBay

any feedback will be helpful...

thanks