The 50k cars you speak of are generally the better end of the spectrum, often with serious $$$ spent on restoration.
To put it bluntly a LHD car just won't suit the majority of people when they have the option of RHD. Probably not even me, and I have a LHD Mustang.
Despite Zeds being built in both LHD and RHD form there's still a fair bit of work and time and expense converting from one to the other, it's not that straightforward, I looked into it a few years ago when I discovered that a contact had a tidy non-rusty 240Z sitting in his LA yard.
It all comes down to preferences and competitive $$$, as always. A LHD car would, IMO, be worth the same as an equivalent RHD car less the conversion costs should conversion be req'd down the track in order to on-sell it. My opinion, I think realistic, but others may disagree.