Where do you find/buy your notes?

I'm wondering where do most of you find your finds?

I'm newish to buying often. My collection only started through inheritance decades ago.

I regular antique shops, go to 1 show a year, coin shops and eBay. I worry about a note being authentic through online without being graded. I know only buying graded notes would defend from counterfeit paper but sometimes it's out of my price range.

Any places I'm unaware of would be great advice! Thanks.