I had it done at Flat 6 Innovations by Jake Raby - known for quality work, and solidly booked very often and sometimes tough to get your car in. The "basic" job of installing the IMSR also includes a new clutch and some other things like a new RMS too. It ran me around $3000, but while it was all opened up I had some other things done - new water pump (they are known to fail due to plastic blades), new lifters to quiet the car, and a bunch of other stuff. I think it's worth it, and if you have the money to do it I wouldn't hesitate. The engine can range from $9K-$20K, and you don't really know the history of the engine in some cases. I know my car had 12,000 miles on it when I bought it.
Steve