While it's not manufactured by the same company anymore, a Korean company bought the formula and sells it on Amazon now! [0] So, you, too, can see what the hype is all about, if you want! At $0.39 per piece of chalk, it is, indeed, expensive. But, it is also a much different experience from writing with ordinary chalk.
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[0]: https://www.amazon.com/exec/obidos/ASIN/B01HDNUXBW