That's close to the price I paid. I think it was less than $15..
I forgot where I got mine, but I think it was with another order,
probably a coil, or coil cover, etc, so the shipping was probably
not much more than the other item alone.
I've seen two versions. Yellow with black piping, and I think Garrett
sells a black version. Mine is one of the yellow ones. When I got it,
Garrett didn't sell one yet. Mine was like a 3rd party cover, but
looks about the same as theirs, except for color.
Like I say, I think the best plus to one is keeping dirt out of the buttons.
The pinpointer button in particular. But I like the protection if it gets
whacked against something too. Adds a bit of cushion..
But like the coil covers, which I also have for all three coils, it's
kind of a option.. Not really required for normal use.