Here a couple of articles detailing the costs of the 2020 elections for Fulton County, including $6.1 million for the January runoff:

From the Marietta Daily Journal:

"Richard Barron, Fulton County’s elections and registration director, said the costs of its elections for 2021 and beyond are going up.

After the county spent $38 million for the entire 2020 cycle, plus $6.1 million for the January general runoff, it plans to spend $7.2 million on the 2021 municipal elections in November and a to-be-determined amount ($2.46 per registered voter) for the municipal runoffs the following month."

From the Atlanta Journal-Constitution:

"That’s why Fulton County spent a record-breaking $38.3 million to run the blockbuster 2020 election cycle. But officials expect elections costs to keep going up.

To put the $38 million presidential pricetag into perspective: Fulton spent $9.9 million in 2016 and about $6.1 million in 2012."