Gold plating pricing

I have some gold plate on sterling silver silver pins that I made
some years ago. They were plated by a professional plating company.
The plating was 18k yellow gold. At that time I had them cast and
made a small number of each piece–plated one and kept one or two in
Sterling. Unfortunately I have no record of how much it cost to have
them plated. Now I want to sell them and I wonder if anyone can give
me some idea about how to price them. Approximately how much more
should they cost than the Sterling pieces?

I would really appreciate any suggestions!
Thank you,
Sandra
Elegant Insects Jewelry

I have some gold plate on sterling silver silver pins that I made
some years ago.[snip] Approximately how much more should they cost
than the Sterling pieces? 

I have no idea, but if you have both, you can weigh them and
compare, to get the gold weight. Or you could call Red Sky Plating
and find out what it would cost now to get them plated.

Noel