I have the wide and tele lenses for both the Heligon and Xenon, and one accessory optical plus sportsfinder for them. The T1 close-up lens for the tele lens. Two sportsfinders for the 50mm. Tripod adapter, sun shades and filters. I also have the document copying stand, but have no use for it.
I can't say that I'm a big Retina collector, but I have a couple and like to use them. They are my favourite 35mm cameras.