The amount isn't too far off I don't think. I'm no font designer, but four man years (including overhead, etc...) isn't insane, nor is that figure off for expected salary.

That said, I'm very mixed on this kind of "ransomware" development. If you want to share, share. If you don't, don't. But front-loading the costs of your proprietary software product on people who actually want free software is borderline unethical, IMHO. Obviously people are free to pay if they want to, but if you really want to support free development there are better targets.

he actually elaborated on that and said that after fees and taxes it would be $96000 and that it would last him for about 800 days to design every charackter.

4 years as a side project would be my guess.

That's less than $ 25,000 / year, or around $ 120 / day. I don't think you can find a decent designer for $ 120 / day.