It's not really easy to estimate development cost of Nintendo games. The ruler of "100m US$" for AAA games can't be applied to Nintendo games, most of them don't get close to that and some only do near that with marketing included.
Super Smash Bros Ultimate was believed to have reached that cost with its extended development(game + 3 years of DLC), huge team and licensing.
Tears of the Kingdom, though, got a development cycle of 5-6 years and had more people working on it than BotW. I think that game maybe surpassed SSBU budget. Something around 100m $ is my guess. But we really can't be certain without Nintendo informing it, and we can't make easy counts like "600 people x average salary x 60-72 months", because it wasn't anywhere near 600 people working on it at the same time throughout all development, there was the time of pre-production and early production that was likely mostly EPD and Monolith leads and other factors.