Two years ago I had a shaft turned down at Joe Blackburn/Steve Lomax booth at the expo. They are the best in the business. I think it was $40 or $50. I only went from 12.9mm to 12.5mm and they told me that was a lot of wood to take off, but I didn't care. The shaft stayed straight, but the hit changed, and I didn't like it as much after that so I sold it.
BTW they get very busy so drop it off at their booth as early as possible, I did that and it still took like 5 or 6 hours for them to get to it.
Hope that helps.