Because they are a nightmare to own. So lovely when they work but so frustrating because you keep readjusting the shutter mechanism with those tiny screws and you end up wasting so many rolls (and pictures) in the process.
I own a 35GT, barely use it but wouldn't sell it because I have too much empathy. It would feel like receiving money to spell a malediction on someone.
Coincidentally I think I have a non-working 35GT in my market stall (https://camerasetc.wales), so if you want a project drop me an email as I'll send it to you for the cost of postage. I have too much in my repair backlog and those things are fiddly little bastards at the best of times :D
I too have too much clutter so I will have to turn down your kind offer but I will peruse your sites and I may ping you a note sometime about a particular lens I have been looking for — quite a random cheap old one I regret parting company with. (I'm in Kent but I have a friend in Cardiff and if my wallet does not protest I may pop in on your stall)
That reminds me that I need to do a new update post, whoops. I've had an absolute buttload of Pentax K mount gear the past couple of months, which is quite annoying as I don't have that many customers that shoot it. I'll have to big up the Pentax cameras a bit more haha.
Do swing by if you're ever in town when the market's open! I've always got lots of fun cheap stuff kicking about, and a bin of broken shit if you need parts :D