IRV would have saved Pierce County $250,000 in 2005
The September 2005 primary in Pierce County cost $665,954. The only primaries held by the county itself were the Charter Review Commission races. Indeed, there were some precincts where the only races on the ballot in September were the Charter Review races. Pierce County's share of the cost was $257,697.45.
If Pierce County had utilized Instant Runoff Voting to elect its Charter Review Commissioners, it would have saved that entire amount. But there were 24 other jurisdictions which held primaries in 2005 in Pierce County. While the total cost of the primary would have been lower than $665,954, it would not have been $257,697.45 lower. There are certain fixed costs associated with holding an election that would not have gone away, so the various cities, school districts, fire districts, etc. would have had to pay a higher amount without the Charter Review races. If Pierce County were to adopt IRV for county level elections, these other jurisdictions would observe this ability to reduce their own costs and probably look to adopt IRV for their elections as well.
What impact would the adoption of IRV have on the Metropolitian Park District of Tacoma for example? In 2005, there was one park commissioner race which attracted three candidates. This meant in the current system that one race cost the Park District $65,151.41. The person who eventually won the general election won over 60% of the vote in the primary. The Park District probably would not have a hard time figuring out where they could spend the money they could save by moving to IRV in electing their Commissioners.