On other forums, I keep seeing modern (present-day) issues from other countries posted with the question, "What is it worth?" Some of these collectors are asking about high denominations too, like a 2018 Hong Kong $500 from the Bank of China:
https://en.numista.com/catalogue/note203190.html
This note is being sold on eBay for about $100 USD. Although the collector was posting about a common repeater, I can't imagine spending $125 (or any premium) on such a common note. If you check the Numista link (provided above) you will find that 92% of Numista members own the (2018) $500 while only 18% own the 2020 note. What does this indicate? Not much since its only 2023 (& we need more time) but if I were a collector from Hong Kong I would save my money or place it elsewhere. What can $100 USD buy? It can buy a lot of nice notes.
You could collect according to motif (Music, Nobel Laureates, UNESCO world heritage sites featured on notes, etc)
You could collect notes from specific regions (Asia, North America, Europe, etc). Could somebody with $100 buy a note from a nations which no longer exists (Biafra, East Germany? etc) or which no longer issues notes (Ecuador, El Salvador)? How about banknotes that are just gorgeous designs?
Here's a few recent World notes I picked up. The first is from Solomon Islands (1986) $50, the 2nd a $5 polymer replacement from Fiji & the 3rd is a $50 polymer from Triinidad:

- Solomon_$50_P17.jpeg (302.7 KiB) Viewed 33966 times

- Solomon_$50_P17_r.jpeg (298.35 KiB) Viewed 33966 times

- Fiji_$5_P115_rep.jpeg (298.25 KiB) Viewed 33966 times

- Fiji_$5_P115_r.jpeg (297.19 KiB) Viewed 33966 times

- Trinidad_P54_$50.jpeg (308.11 KiB) Viewed 33966 times
All together, these notes were less than $100 USD.