Ok I found a case that works for Sony PRS-505.
It's a case for Kindle Paperwhite sold under a strange name of
ZOENHWA.
Not exactly a luxury version but it fits.
Paperwhite: 174×125×8mm
PRS-505: 175x123x8mm (measured by me - official specs differ from what I measured a tiny bit)
Will update this post once my Amazon review is online.