I don't think amels are very common in nature. The sun is your enemy when you don't have melanin.
The most recent thing I heard on wild Anerys is that parts of Florida have something like 10% of the population expressing anery. (?) It makes sense, though, I see no reason why anerys would suffer any survival disadvantage.
I haven't heard of any other mutants (caramel, lav, blood, hypo, motley, striped, etc) being found commonly in the wild.
I've never heard of any breeders letting corns go.