They are cheap because they are cheap.
They are a budget low production cost item.
You can run them, just keep in mind they are noisy and were never ment to be quiet.
Iirc they were offered (to the shop i worked at) d44 for under $100 (wholesale price)
I dont recall ever installing any as the majority of our work was dd type diffs. Yes we did offroad trucks but not much for hardcore/crawlers