In 2011, Wisconsin held a statewide recount on the state’s Supreme Court race. Cost for that recount according to the LA times was $520,000. That recount was for 1/2 as many votes as for this one. Even with inflation, it shouldn’t cost more than 2x as much to count the votes.
The Wisconsin Election Commission released the estimate with county details here.
county_estimates_presidential_recount_pdf_10008