IIRC it is $200 for a reflash and $1000 for a first time flash. (Mastro's site is down)

I suggest finding an ECU that's already tuned with ECUtek for $400 max, and then have them reflash it for $200

400 + 200 = 600 << 1000

This was similar to what I did, but for my WRX. The hard thing is trying to find an STi ECU tuned with ECUtek, but I'm sure they are out there.

Good luck,
Eric