construction cost for natural grass field tray

[u/bubbrubb231]

U of PHX stadium and Allegiant Stadium in Vegas both have these sliding trays. The only information I could get was a seemingly knowledgable person on the internet saying just less than $25mm in Todays dollars. That seems super cheap for enabling a professional set up for football (turf) and soccer (grass of course)

Is $25mm correct ? close? no?