I have one of these keys and it is very nice. Many Miata nuts have been looking for these, and since I found a source for them, I wanted to share.
Silca UltraLite colored key blanks for NA models on ebay.
Coming out of Finland, $15.99 shipped. I just bought a red one. Already have a green one. These are sweet, but will bend if you aren't somewhat careful with them.
Here is a link to the guy's auction. Currently available in six colors: light blue, dark blue, green, orange, gold, red.
http://www.ebay.com/itm/UltraLite-co...%26&rmvSB=true