Back when I had a studio I had a small collection of cheap vintage cameras I picked up at flea markets and yard sales. The hope was always to find one that, through its flaws or light leaks, or whatever, might produce some interesting 'mistakes' in use. I don't recall any of them actually succeeding in that way (a Holga or Lomo, etc were easier to coax 'good' mistakes out of), but they were cool to just have displayed on a shelf....