While developing this cost estimation tool the question was asked where is the bulk of the information coming from needed for the cost estimation, the answer was the following:
30 Ask supplier
18 Supplier resources - Supplier factory visit
14 Request for Quotation
7 Run@Rate Production Trial Capacity
5 Supplier resources - Financial accounts and statements
5 Contract review
This gives another clear indication of the importance of data quality in the existing process and procedures as well as getting in actual contact with the supplier, cost estimation can not be done without seeing the process and interacting with the supplier face to face.