I don't collect paper money. I do hang on to interesting and obsolete pieces when I see them. One I do like is this $10 I got in change some time back.
I thought about that too. It would have been nice going one more digit. I could put it on Etsy as a major error.
I usually collect any paper money I find. My wallet likes to eat it up, and then it magically disappears and turns into another ebay coin purchase...
Currently I'm concentrating on New Zealand and Australia, filling in gaps, replacing notes as better ones come along. I have over 80 other countries notes in varying numbers. Here's an el cheapo Brazil I got recently. Not a favorite, but it means my Brazil collection has increased to 6.
Been working on a graded US $1 type collection for a while, but I tend to get distracted with other collections. About once a year I get the urge and fill one of the slots. Only ones that I need now are: 1869 US Note 1886 Silver Certificate 1923 US Note If I ever manage to finish it then I'll post some pictures. Should be about 3 years from now!
I here that, have several paper money collection going, MPC and Disney are the main ones, but GOLD investment is closing in fast