Numrich lists them. www.e-gunparts.com
Millet makes a replacement. The old Accro will fit but does not give the "barn door" sight picture. Cheaper, though.
I don't know anything else that will fit without remachining the slide.
Try your factory parts in the Brownell Catalog I saw them there.......Millets will work if your looking for a replacement. I also have a extra Accro that will work and some spare elliason parts if yours is broken...Just email me if interested