Since you've mentioned it, did you buy your 650 during that brief moment they were available at the Sony Store or did you find it elsewhere?
I should also mention that cases for the PRS-650 in stone-oiled leather are available from hmcurriers on Etsy:
http://www.etsy.com/listing/67926425...-kindle-3-case
Cases for the PRS-350 cost ten dollars less than the Kindle case in the link and are therefore cheaper than the official lighted Sony case, since HMC offers free shipping. Since Octovo, Saddleback Leather, M-Edge and Noreve don't make cases for Sony readers, these are the only vintage leather cases I know of being offered for the x50 series.
There's no picture for the 350 or 650 case because these are new options that I and another Kindle Board member asked HMC to consider. Happily, they considered the idea and accepted it.