I agree that $150 per wing might be a bit low, especially if you have to have someone come in for one plane. I suspect though, that most shops will have multiple, if not multiple dozens, of affected aircraft. Get them all lined up and done in one day.... the actual inspection takes minutes... it's the R&R of fairings and bolts that that takes the time. So even if it costs double.... are you willing to roll the dice for $1000?
FWIW, I can't find the post now, but a member of the pa-32 Facebook group reported getting it done when piper released their SB. He flew to the inspector, total cost as I recall was in the $500 neighborhood.