Hi,  you should _never_ have any projection-less musical box discs
nickel plated as it will make them much thicker and this will upset
the adjustments on the star-wheels.

The easiest thing is to use wet and dry paper to rub off the rust,
using medium, then fine, then very fine paper to get a nice smooth
surface, remembering that the makers said a very thin coating of thin
oil should be kept on the surface of the discs -- although, personally,
I have never done this.

Quoting a price is difficult without knowing if you have a single or
double comb model Stella.  Prices are up and down a lot at the moment,
but $500 would be a reasonable price, in good working condition.

If you want additional discs, I have over 2,000 in stock including a
small number of this size.

Sincerely, Kevin McElhone
Northampton, UK