The first thing to understand about this fiscal analysis is that it is written by someone who has a lot to lose. Those whose job descriptions could be rewritten by a charter, like CEO and BoS, aren't going to risk having that power taken from them.
The bulk of the low-ball estimate of costs to the county for Measure W is in the estimated of hours for services of the County Counsel at $246/hr. and county administrative staff at $333/hr. Both County Counsel and county administrative staff get paid the same monthly salary no matter what they do. They are our public servants. How much does Democracy cost?
It also makes assumptions about how many voters will want copies of the entire charter once, in the future, it will be ready for the ballot.
The medium estimate includes a small travel stipend to the Charter Commissioners, hiring expensive outside consultants and 10X more of the County Counsel's time at $246/hr. all at the discretion of the Board of Supervisors.
The highball estimate is just in the case the county has to step in and micro-manage the charter drafting process. One wonders what would authorize that sort of intervention? The Board of Supervisors can legally submit their own competing charter.
It also assumes it will be in a Special Election, which alone costs $100,000-$150,000. Although GC § 23710 says it has to be a Special Election, GC § 23712 says it can be either a General or a Special Election.
Additionally, it adds in the cost of a minimum of 25 community meeting at $100/each; that would be lovely. And another 50% more of County Counsel's time. And some very generous benefits for the Charter Commissioners including up to $500 in incidental expenses per meeting, $thousands for space rental, and per diem meals for Commissioners. No wonder its so high!