To be honest, you cannot apply a dollar value to the costs of an MDM project plan as it differs from company to company and solution to solution.
For some companies, the expenses of an MDM project can rise up to $100K/month taking into factors like software licensing, storage, implementation, talent hiring, training and maintenance, and support.
For others, it could be just $10K/month if they already have a team and are just using an affordable MDM solution to master departmental records.