Here's one I found. It's not just the shell, it's the whole fob apparently. But I found a locksmith near me willing to get me the fob, program it and cut it for $200 and it's guaranteed to work, so I'll probably just do that.

So my FOB key got wet and some of the functions stopped working. I ordered an aftermarket replacement off Amazon. I brought in my original key and the blank replacement to a local locksmith. They cut and programmed it for me. It works like a charm! Overall I probably spent $100? The dealership wanted $300 for a replacement. My car is a 2014 so you might need to do some searching for the year of your car and calling around to get a good locksmith rate. FOB replacement