I used to work at a camera store. There was a box of old parts sitting beside one of the salesmen's desk. I asked him if it was up for grabs and he said "no" but if you want the stuff, its $300 for the whole box.
I thumbed my way through it all, lots of old Arca Swiss basic stuff, and offered him my $300. When I took it all home, I sorted it and dusted it all off and found that there was a complete 6x9, 4x5, and 5x7 systems. As well there was an 8x10 but it was missing a bellows and a standard. I bought a new one on my next pay day and sold most of it over the next six months. I honestly can't remember how much I made but it was back in the mid 90's when there was still a thriving commercial market for them.