There's not much looking around needed. I can't speak for everywhere, but in Europe they're all over the place. The black, overbuilt Singers and Pfaffs can be had for less than €30, very often €20. The later ones are plentiful.
I refuse to believe that these can be bested. The only obstacle I've ever seen in operating these is user-laziness. People have been made incompetent by having machines that do too much for them and are then completely kneecapped when a problem arises, often a simple one.
One or more non-metal gears turn up in machines as early as the 1950s. Loads of the early zig-zag machines have a nylon gear in the zig-zag mechanism, with the rest of the machine being metal.