Perhaps it's because I've never worked with chalk daily but chalk never felt better than whiteboards to me, just thinking about a chalkboard makes my teeth hurt.
They were closing due to the old age of the owner/operator, but he sold the method and apparatus to a company in South Korea who makes it in plentiful quantities now. Hagoromo.
Quite seriously, if you know the right people, those who hoarded it, it's available. Or buy the Korean stuff; they still make it. Its become a weird business.
Nice Japanese chalk on a piece of slate sanded to the appropriate roughness is silky smooth.