This was my post in answer to a question posed in a real estate forum. I feel like it encapsulates the question of inspection.
I am not convinced an inspection (of a typical co-op) is worth anything more than peace of mind for the money spent. This has also been the feedback from most of my clients that have utilized their service, post inspection. Most of the things that will be uncovered are usually quite obvious. I also don't see the need of an inspector going into the basement of a 200 unit building and "inspecting" the massive boilers.In a co-op that is fiscally sound they will have the means to make repairs on the internal elements such as wiring, plumbing. Most of the important information will turn up in a review of the building minutes and by asking the managing agent for information on the age of the roof, boiler and elevators (though elevators can run for a long time with proper care and rebuilding). Also ask when mandatory facade work will be required next.
If you are purchasing a prewar co-op you will want to know about the plumbing and more importantly the electrical wiring, simply ask the super. many older buildings will have a hard time keeping up with modern electrical demands, some good info here.
For smaller buildings(especially 6 units or less) or condos where you are responsible for the HVAC system I always think an inspection is in order. I would also want an inspection/engineer/architect to have a look if I were doing a gut renovation of any "estate condition" home.
The inspections that I have been part can cost from $500-$1000 dollars. Perhaps a small price to pay for that peace of mind at the end of the day. But don't expect much. That said if a client requests an inspection I would never challenge it, but I do give my opinion if asked.