I guess I can join this club now. A few hours ago I looked in a charity shop and found an XR Rikenon 28/2.8 which looked to be in pretty much new condition apart from some fingerprints on the rear element. It had a filter on the front. The lens was $8.75.
I don't know anything about this lens or its reputation - can anyone enlighten me?
I just had a short while before the sun went down to try it out on my K100D. It seems quite sharp when I get the focus right, though I can't remember when it was stopped down and when it wasn't. I have B&W'd 2 of the shots as I thought it suited them. I did think some greens (plants, not in the shots below) were a bit less green than usual, but that was probably due to the weird warmish light in Adelaide late this afternoon.
I don't think I'll have any problems getting $8.75 worth of enjoyment out of it.