Really i don't see any advantage buying physical bitcoin designs that are made by some persons.
The 100 trillion dollar Zimbabwean note was worth around 25c when it was an actual currency. Now it's obsolete they go for $10-20 all day long on Ebay.
I love those notes!
Going to buy one for my collection. Didn't know they cost so much now though. $10-20 for a note? I think I can buy like for $3-5 where I live, at least the price was like that some time ago, but maybe it's too late now for that cheap price.