About £100 each I think, but a lot of the problem is just carbon build up on them that can be cleaned.
This problem is getting more common if you notice these cars get more miles on them 
This is very true.
Try a can of BG44K in the fuel tank, that will help to clean the carbon off the injectors.
The TFSI's are dirty engines and as a result make a lot of carbon - you can see the amount of black smoke they throw out when tuned (tuned K04 setups are the worst for this)
They seem to like a good thrashing to keep them clean so don't be afraid to give it a good spanking now and again
Dirty inlet valves are inevitable as these engines get more miles in them. This will affect the idle and the starting
