For spare / repair parts aliexpress unfortunately is still the heaven. Sure you have to be really careful who you order from, but sadly the modern world hates selling spare parts and loves e-waste (especially for smartphones, it used to be different before ...).
Or eBay. I’m offloading a bunch of random bike parts, and yeah, somebody out there needs a Shimano XYZ-123 that was last built in 1994 (and doesn’t care to figure out the modern replacement).
