The cameo backs I bought online were originally silver and sold in a 12 pack, the flur delis I made a cast of and hand pressed FIMO clay into it to reproduce the shade. Once i glued them on I spray painted the whole thing gold.
Etsy is a great place to find jewelry finding including Cameo Base Setting.
This is the style I bought.
http://www.etsy.com/listing/62066354...c et=supplies
More from etsy
http://www.etsy.com/listing/79715176...cet=suppli es
http://www.etsy.com/listing/71109978...ref=v1_other_2
http://www.etsy.com/listing/74130427...ref=v1_other_1
Also has more option if you want different backs for the manga interpretation as seller tend to have more then on style in there stores.
http://www.etsy.com/shop/kinacraft/s...craft&pag e=1