Mario is right, it is expensive and if you add a consultant it is even more expensive. When I said it opens doors, I was talking about larger clients. I know some of our large clients require certifications. It all boils down to what are you as a company wanting to become. If you are going to go after the whale's, you will need certifications. The link Mario posted should give some guidance on how to prepare.

One other piece of advice is if you are going to get multiple certs, you might as well do them at the same time.