I'm sure there's others, but I'm partial to The Lucky Labs. They have a white carbon fiber decal set for both front and back. Easier than replacing the glass if such a thing is even possible.
I have replaced mine a while back with the whole kit. Did the swap myself. Pretty easy if you just take your time. I like having the option to swap back and forth when I want.
ifixit.com charges $170.00 plus shipping to swap all the parts which I see that a little pricey...having said that I was comtemplating going that road but I'd rather upgrade my line to the new 4's and spend about thesame amount.