I’ve only played with one of the cheaper Lensbaby models, and the plastic, creaky construction made me nervous, although it was fun to play with. Their new Composer Pro is supposed to be the best-constructed yet, though.
It boasts metal construction and a better focus mechanism, which will feel better under the fingers of a pro photographer who’s used to heavyweight accessories and L lenses. It’s compatible with the existing “optics,” and costs $300 with the default “double optic” or $400 with a Sweet 35, the popular new wide-angle optic.
If that seems a little expensive, reflect: it has pro in its name.