OK, I'm one of those cave men, uh cave persons who carries and uses cash. Even worse I use $2 bills..
Boo hiss from business owners gallery. Wait, put down the torches and pitchforks, I very rarely buy things with them, I use them for tips.
At hotels the maid finds three pristine, uncirculated, consecutive serial numbered $2 bills. The next day the next three serial numbers, for as long as I'm there.
The best is the reaction from people who don't expect anything.
I had a blood test last month, and I don't know if the phlebotomist was having a bad day or she's normally brusk but as I was leaving I slipped her a couple $2's and she lit up a smile that could serve as a lighthouse. I think I made her day and I know it made mine.
Get to the point. I got some Tis-the-Season catalogs in the mail and the PBS catalog had a couple legal tender $2 bills that had been altered with colored pictures. One was the 150th anniversary of Yellowstone NP, and the other was the former Queen and current King of England. They were saying they're still legal tender but I know if they were spent/turned in they would be destroyed, not stay in circulation. Of course if you spend $30 to buy one you're not likely to spend it. I wondered if other people were selling these or other bills like them so Googling we go.
Boy howdy are they ever, but scrolling down one place I got a bigger surprise. There are dozens of people who sell US paper currency, Not the $500 priced $10 bill rarer than hens teeth, just normal everyday notes.
First they show normal 100 note packets I buy but that's not what they're selling

I didn't get into the other denominations I was having enough trouble getting my head around the $2's.
I also noticed several sites with variable pricing depending how you paid. Here's two of them...

Most of the sellers claim to have sold a lot of packages.
I can understand Grandma/Grandpa want 5 $2 bills for the grandkids Xmas stockings.
Maybe the bank teller brushed them off. But there is a lot of stupid people if the sales claims are half true.