Nutone ceased making the Food Center and its appliances a number of years ago. Ebay is one of the few places that accessories and parts are still available. There is a knife sharpener (Buy It Now $25) and a complete mixer (Buy It Now $55) currently listed as well as some parts.
http://shop.ebay.com/i.html?_nkw=Nut..._from=R8&_ipg=