I don't know that those lenses were ever sold separately, but I've had several cars with them and have had very good results using a fine scratch remover on the outside, and cleaning the inside per the FAQ. They come out close to new.
The lenses do have a tendency to come off, and I've tried several types of adhesive to re-attach. A two part kind that is seriously toxic seems to work very well.
If you try this and they do come off, do not allow anything to come in contact with the silver material on the inside other than the cleaning mixture as mentioned above.