I've enjoyed reading up on the Rs4 and after some thought the wife fancies one as her new daily drive

Theres a few cars we have seen advertised at various places and have narrowed it down to two which we will be looking at over the weekend.
The first is this one
http://www.audi.co.uk/used-cars/used-ca ... =se_na_re_
one owner,low miles,full audi sh and one year audi warranty with the sale. I know its a bit dearer than some,but with the warranty its piece of mind motoring for a year.
Also fancied looking at this
http://www.bossperformance.co.uk/used-c ... 2498026537
A bit cheaper,07 reg ,but more miles. They will probably give more for our part exchange than a main dealer.
Whats peoples thoughts.?
This will be our first performance audi so we have no idea on real world servicing costs,spare parts prices and the dreaded fuel consumption

The wife travels 2miles to work everyday so hopefully the fuel wont be too much of a problem,cant be any worse than my 380bhp/370ftlb lancer evo which she sometimes uses to go to work.That does half a tank in 3 days on her commute!!
Money is not an issue for us but we dont want to spend £23k on a car only to need new brakes,tyres and suspension after a couple of months!
Any info would help.
Thanks , Evo.