Thats no Moon, Thats a space station!
Depending on how handy you are with a spanner etc i would do it yourslef if possible as all except the Haldex stuff can be done with normal tools etc. Plus you get the satisfaction that A) its been done right B) No corners have been cut.
Haldex does require specific tools so i think when i get mine serviced i will get it done at a local VAG specialist.
As said above an Audi stamp in the service book isnt worth £300 more
Audi S3 8L BAM 225 2002 - Ming Blue : Silver Heated Leather, Armrest, RNS-E & Bose, Alloy Mirrors, Gunmetal 18" RSTT`s, Sunroof, Cruise, AutoDim Mirror & usual S3 extras.
Mods : Revo Stg 2 & Select+, FMIC, 3" DP & 200 Cell Cat, 007P (New Piston), Jetex Filter & 80mm TIP & Heatshield, LED Sides & Fogs, Gen VW Aero Wipers, Full Powerflex Kit, Lowered on AP Shocks & Springs, 15mm Front & 20mm Rear Spacers, N249 Delete & Catch Can, AP TVR 4Pot Brakes & DS2500`s, Sachs DMF & Carbon/Kevlar Clutch