Out of curiosity, I did some spelunking. The US Department of Labor has stats[0] which summarize county-level "median yearly prices for one child at the market rate." Still TBD what the comprehensive data show at P99. That said, among the county-level medians, it appears the maximum estimated cost in 2023 is in Arlington County, VA, at $28,747 for a single infant, which is $2400/mo.
Most people play $1,500 to $2,500, for dedicated daycare facilities with the prescribed 4:1 or 7:2 teacher:infant ratio.