IHI vf34 $699 (<£400) from the US (google it)
Manifold-£500 (full price from jabba)
Oil and water lines <£100 from any hydraulics
shop. (or pay jabba a little more)
Injectors-£200 (440cc from the US)
Maf tube-free
Pieces of silicon hose for turbo outlet, +maf to intake pipe joint-£15
Modified inlet pipe to fit turbo-£5
Fitting £300
I reckon thats £1520.
Still got to get it mapped though and do a little work yourself to work out the fittings you need.
You may also want to get an uprated fuel pump. The S3 one is £120 from the dealers, or you can source a non VAG one from the US for half that.
It just takes a bit of bottle to sort it out for yourself
Edited to say I forgot the turbo to downpipe adapter. Jabba charge £150 ish for theirs, but I'm sure you could get one from anyone making scooby exhausts for a lot less.