I assume you are asking for a half frame with a range-finding, i.e. distance metering mechanism, and aperture plus speed controls.
At the low end cost I have searched and found nothing. Yet out of the blue, here at RFF a guy offered a small Canonet f1.9 custom adapted for half frame. According to the friend of the seller the story was that such cameras were in use by the Australian or NewZeland police.
I do believe that some highly professional job was done, because it included half frame marks in the viewfinder - alike those in any normal Canonet GIII.
Of course I rushed to buy it and was ready to pay whatever. I have used it recently with fujicolor 100 and it is very much ok.
All in all, this opened my mind to the possiblility of looking for a qualifyied technician to do the same job with any camera. After all the job requires two steps. The easy one is inserting two metal rectangles that will shorten the film frame to be exposed. The hard job is readapting the winding mechanism to wind half frame and cock, instead of a full frame.
Then perforating the metal bright lines small plate,that produces the bright lines in the viewfinder - this is a job I do not believe any technician will be able to do. But the good news here is that you (your supposed technician) can achieve a lot by tape masking. At the end then you will have a view like in a Contax or Kiev, without bright lines.
Cheers,
Ruben