Well mine was via the Autronic SM4 ecu which was £1420 fitted, but this was obviously not fitted for just for anti-lag, i chose the stand alone ecu for my forge builds. I also had Launch control on 2 of my cars too, now that,s amazing, holding it @ 5k revs and then just let all hell loose..Lol.
I,m sure you can have Anti-lag via Ecutek, well i know you can a few of my friends have it on there Evos.
As for the Simtek, i think that,s in the region of £1200 or so too....