In addition to the expected functionality, I also bought the visor because I wanted to buy original accessories - of course I would be happy to buy the visor cheaper, but no alternative, however, the panel is in no way - at present (12/2013) there are the following alternatives:
Sony ALC-SH114 (spare part: Sony ALC-SH114 Hood, 429 139 201)
JJC copy (New: Metal Lens Hood JJC LH - LHP-1 for Sony RX1)
Delamax copy sunshade DHP1 for Sony DSC-RX1 (bayonet mount, metal, similar LHP-1) black
Fotodiox in Leica Style (Fotodiox lens hood for Sony (Bayonet) Cyber-shot DSC RX1 RX1 Digital Camera)
In the United States there are in the bay already clones from EUR 10 in full plastic.
While the JJC / Delamax are functionally almost identical to the original accessory, the Sony ALC-SH114 is clearly "clunky" - for it shields the lens better. As usual SLRs can mount them reversed - in the original leather pocket camera no longer fits. Here at Amazon ALC SH114 seems probably be rather rare to find, outside of Amazon you get it anyway much cheaper.