I had my 17x8 ROH Snypers for the rear widened to 17x9.5 by Weldcraft in Michigan. Cost was $175 per wheel. Their number is 734-420-2211. They seemed to have done a pretty good job. I have yet to mount the wheels on the car yet but here are some pics.
Before widening:
After widening:
A pic of the weld:
Another pic of the weld from the inside:
Nitto 275/40 Drag radial:
Nitto 275/40 Drag on an angle: