That seems a little high, that sounds like a lot of hours. The labor on my IMS retrofit was less than that.
Are you a member of the PCA? There may be some local DIY folks in your area that could help you do it. Maybe some folks from here are nearby?
Independent Porsche Repair | Repair Shops Specializing in Porsche | PCarShops.com may have something for you, and Kevin McConnell at The Porsche Specialist is right up the road (Edit: 2 hours away so not right up the road...) in Broomall, PA. He is the one that did my IMS; I highly recommend him.
Steve