They’re not really sold as currency - they’re sold as souvenirs. If you visit the Bureau of Engraving and Printing in DC, they’re for sale at the gift shop. I’ve got a set of 32 $2 bills hanging on my wall right next to my set of hyperinflation Zimbabwean currency.
If you just want $2 bills, go to your bank. At my bank I need to order them $200 at a time. When I was flying every week they were great as the bartenders at the airport lounges would remember me as the “the Thursday $2 guy”.
But these notes stop the printing process early—the purchaser is on the hook to cut them out. So these should cost less than the fully printed and cut bills if we're going by pure cost of creation.
Do banks pay upwards of $1.50 on the dollar for new bills?