Green-polyped, or green base? The green-polyps are much harder to find and much moer expensive. I bought mine from a LFS about the size for a quarter for $80, and I consider that a good deal. The green-base toads are much easier to find, and most LFS would get one or two in fairly often, or at least they do in my area.
Many poeple would sell either of these green toads, just have to look around often on some forums. And when I say often, I mean daily because they do sell fast. Other online sources are not allowed to be named.
Here's a pic of my green-polyped toad when I got it.