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, 18" RSTT`s, Sunroof, Cruise, AutoDim Mirror & Usual S3 Extras.
Mods : Badger 5 Stg 2 Custom Map, FMIC, 3" DP & 200 Cell Cat, 007P, Jetex Filter & 80mm TIP & Heatshield, Complete LED Kit, Gen VW Aero Wipers, Full Powerflex Kit, R32 RARB, AP Shocks & Springs, 15mm Front & 20mm Rear Spacers, BB Uprated Actuator, N249 Delete & Catch Can, AP TVR 4Pot Brakes & DS2500`s, Sachs Carbon/Kevlar Clutch