Just check eBay for Mazda fob covers. Even though eBay may say it doesn't fit the 124, google search said our fob is same as Miata. I spoke with Mazda in Tulsa and found the fob Mazda uses for all its current cars are the same. You can usually see a pic of the type fob. I just wanted a silicone cover but there are several other styles too.
I purchased a few of these (black,blue,red) based upon this recommendation and they are very nice. Supple. Also, they arrived pretty darned quick by that China Post (less than 2 weeks). So wanted to give these a +1