In the U.S. we have gold (not real gold but real currency) dollar coins. I give my son a couple of those pretending that they’re fairy gold. You can get them from the MTA in NYC. Or I check with local stores and ask if I can buy any gold dollars they have. I try to keep a couple on hand just in case of emergency tooth loss.
Once I was caught without enough coins when my son found the three teeth he’d lost during his stay with his two dads. He received an IOU note written with letters that all had swirls and spirals on each letter (my hand was so sore the next day!) explaining that the Tooth Fairy Assistant 544237 was unable to give him all the money that was owed for the teeth and she would return the following night. It used up all of the ink in my glitter tattoo pens but it was worth it to see his face! The following day he awoke to the rest of his fairy gold coins plus another letter from the Tooth Fairy herself. (I had to ice my hand after that letter!)
For those who don’t know, fairies can take something like a leaf and make it look like real money using glamour. Humans have to spend it that day or it will turn back into it’s original form.