I collect them because people think they're offending me when they call them turds. I also have an impressive collection of Ravens and Tec-9's. I know they are garbage but when I look at them, they make me smile. I'd never use one for self defense.
Some of the more collectible antiques, china, etc. are what were then the cheaper stuff. Things like Staffordshire china which was produced for the working and middle classes. Less of the cheap stuff survives and thus becomes rare.