The most expensive typeface I encountered is JHA Bodoni Ritalic, at €4,401.99 (almost $5,000) for a single font. Although, I only mention it for the sake of being complete, because I feel it’s either a joke or a marketing stunt to get JHA noticed — arguably both.
https://medium.com/@msilvertant/the-most-expensive-typefaces-in-the-world-d025923084f0
https://medium.com/@msilvertant/the-most-expensive-typefaces-in-the-world-d025923084f0