1/2 speed Court and Spark vinyl?

[susan+rick]

While clicking on various links I've saved up in the past year I came upon
this site http://www.elusivedisc.com where if you do a search on Joni
Mitchell you are led to a page that offers a "mint used 1/2 speed Nautilus"
vinyl copy of C&S for the price of $125US. Does anyone know what this is?

Ranger Rick