When looking for parts like this ... would it make sense to look at an electronics supply house?
Maybe try Digi Key or Fry's or Mouser?
https://www.digikey.com/products/en/potentiometers-variable-resistors/rotary-potentiometers-rheostats/84?k=potentiometer&k=&pkeyword=potentiometer&sv=0&pv1=68696&sf=0&FV=-8%7C84&quantity=1&ColumnSort=0&page=1&pageSize=25