It's almost been a year since anyone contributed to this thread so I will resuscitate it. Hope nobody minds.
Here's a note I first saw after ScotsGreyhound posted his in 2019 (yes, 5 years ago). I've seen several other versions & kept thinking I'd like to pick one up. They can be very cheap ungraded but get a bit pricey once they're certified. I was happy to win this PMG 66 example for about the same price I would have paid for an uncertified common example. Its a great example where demand actually plays a larger part in the price then rarity (or toughness to source).
From China (P-874c) 1 Yuan:


This note is quite common but developed quite a Chinese fan base after the model driving the tractor was interviewed several years later. I believe she was in her eighties but I read the article and it was amusing how humble and surprised she was by all the fuss over that banknote design (& subsequent collector interest).