Alas, yes, even circa 2006 I paid as much for an SQ(-A) WLF as I did for an SQ-A body!
I'm not sure what the analysis would be. Seems like the WLF is by far the lightest weight, and folded down is the most compact, so maybe everybody wants one. Or maybe because it is a relatively delicate and complex piece of mechanics they break more, dunno, but in general the prices are brutal. I wouldn't mind having one for my second SQ-A body, but I can't convince myself to pay the going rate. I have 90º and 45º non-metered prisms, so I can still field two operating cameras.