Dragonflypower.com

(Right) The bodies and gears are plastic, the gear pins are wire, frames are aluminum without bushings, lenses are window glass. They sell under several names (like "Equity" and "Advance", imported by Geneva Clock Co, all have the same innards) check the country of origin, and trust your luck to a second hand store instead, any odds are better than these. Here's some Amazon customer reviews: 1 2.

When you get one, verify that the alarm winder will "unwind" when the alarm goes off. I found a "Big Ben" (Left) that belonged to my dad, which has been running for 25 years, but the winder doesn't "unwind" when the alarm rings so I can't use it. The construction of the "Big-Ben" is entirely brass and iron, with rubber seals and "jewel" bushings, the only plastic is the lens, which (unlike glass) will probably survive getting dropped on the floor. (Bonus: it has a robot face!)

I probably shouldn't dis the Chinese import brands to harshly. Though they're made for toys, they have no robot faces or even a shred of anthropomorphic personality, I'm sure that in a dust-free, temperature and humidity controlled, genteel environment with careful handling (like in orbit) they could conceivably run longer than a year, alas such are not the conditions found within chicken coops.

(a note to clock manufacturers: I don't charge for my appraisal services)