I need to write a Project Charter for an IT Project. The work will be completed by external consultants. The technology being implemented is cutting edge and therefore we have no previous projects to use as a basis for estimating budget. I am told that correct PM process means I cannot go out and get some quotes until the Project Charter is in place (because in order to get quotes we would have to commit alot of resource to define the detailed requirements that the consultants would need to quote against). I have no idea if they charge £1000/day or £10,000/day and I have no idea what the timelines would be. Surely I need to get some quotes before I write the Project Charter?
So the question is - How to define Budget in Project Charter when Cost is unknown?