I am informed by the IDA that, for contracts of significant size, it typically hires a consultant to advise on all matters associated with the procurement process. A consultant is only engaged itself after a request for a fee proposal is issued to at least three potential contractors. Such a fee proposal provides a description of the project and the services required in respect of it. The firm that is subsequently appointed then manages the procurement process for the contract in question.
I understand that the costs associated with engaging a consultant to manage a procurement process can vary considerably, depending on the level of services required in each instance. It is therefore difficult to provide an accurate estimate of costs.