No, I don't know anything about the non-MB rebuilt boxes. I would assume a company which is selling their own reconditioned boxes went ahead and bought the tools required to do the job properly.
They should be available from any supplier of MB parts, such as FastLane. They are sold as a regular part, although if a reman/reconditioned box is available, they will want your old box back as a core.
Usually a reman box, if available, will be between $500-1000, or if no reman is available a new one is more like $1000-2000.