The fixed price is not right
Imagine a CRM consulting project with inadequately specified requirements, no clear internal project manager, and ill-defined success criteria. Your consultant bids it on a time and materials (T&M) basis. You're in a rush, no time for a detailed RFP - you know the consultant can do the job, but you need a budgetary number to get approval. We've all been through this drill: somebody brilliant suggests that this has to be fixed price, it'll be easier to get project approval and manage to conclusion that way. You know, just like it would be when buying servers.
But you're not buying servers: you're buying services. While 80 percent of CRM projects are formulaic and could be bid as a "standard project," the other 80 percent of the project work is not only a one-off, but an unknown. Nobody actually knows the requirements, or the ramifications of "something simple," or the shape of your data, or the tricky parts of external interfaces. You may think you're signing up for a three-hour tour, but you're on the way to Gilligan's Island.