my k04 conversion cost me in the region of 450 pounds at the end and thats after selling the old turb, old lines, etc...
i paid around 400 for:
K04 turbo
oil and water lines
injectors of a TT
downpipe (Tho i bought a 2.5'' downpipe for 100 pounds later on)
standard manifold
SAMCO turbo intake pipe
sold k03 for 30 quid, old downpipe for 30 or so, old injectors for 30...
all fitted by myself so no labour costs...
off the top of my head thats what it cost me for the k04 conversion
did it on the engine out of the car too which made it easier, but its not hard at all, tho you do have to modify the oil return line, as it fouls on the
ibiza rear engine mount
EDIT: Oh and youll have to budget for a remap aswell... i run aftermarket ecu, so i just uploaded a new pre made map to run the lot, and i also had an FMIC so if you dont have that, budget that into play...
it was also very easy to mate the standard k03 ally intercooler pipe to the k04 with a 135 degree silicone hose, so if you have the FMIC youll just need the bend to get the cold side of the turbo plumbed in