The most expensive high school football stadium in the country is in Katy, Texas in the Houston area. At least for now.

Next year, McKinney, Texas opens their $70 million high school football stadium. It is in the Dallas-Ft. Worth area of the state.

"I voted against it, but I'm buying season tickets", said one resident.

Back in 2012, a $60 million high school football stadium in Dallas, Texas was the country's most expensive. It includes hospitality suites and a $2 million scoreboard.

https://www.forbes.com/sites/bobcook/2012/08/13/why-allen-texas-built-a-60-million-high-school-football-stadium/#7c9bf77b6e71

The Prosper School District, in the Dallas-Ft. Worth area of Texas, is spending $48 million on their new high school stadium. The Alvin School District's new field, 12 miles southeast of Houston, has a price tag of $41.5 million. The stadiums should open in two years.

A $39 million high school field house was opened last year in Clear Creek ISD.

https://sportsday.dallasnews.com/high-school/sportsdaydfw/2011/11/17/special-report-an-inside-look-at-the-finances-behind-hs-football-in-the-dallas-area

Updated Sept. 1st, 2020

https://www.click2houston.com/features/2020/05/13/these-are-the-most-expensive-high-school-football-stadiums-in-texas/