Too early to say yet as the bikes have only just been available for 12 months.
My first service was 43quid,oil and filter.etc only.The second service is due in a couple of months time so I will be booking it in soon.
BTW,Marco has just had the major 12K service on a ST4 and it cost just under 500quid.
[Edited on 13-4-2004 by KeefyB]