They aren't as popular as they used to be, but you could probably find one at most Targets, Walmarts, and department stores, never mind kitchen specialty stores. They might only have one, but they probably have more in small towns and rural areas where more people are into canning. Walmart.com has dozens of models. Target.com has several, and I was able to confirm online that they're in stock at all of the half-dozen stores closest to me.
And things that were much more popular 30 years ago have a way of showing up at yard sales and thrift shops.
.. and that's only WalMart
The evidence pictures perfectly match the Fagor Duo 6L. This model sells for under $100. It is certainly not the least expensive, but I'd place it at start of the high end.
The UL certification etching on the base indicate current production. A two years old example (used in classes) has no certification, while one current production example does. It appears FAGOR just went through a running change and added the markings to a previously imported model during continuous production. Another manufacturer, Fissler, spent over a year getting certification on a model before it could be imported. I'll take a stab that the CPSC was looking for something to do and decided to hit the pressure cooker arena. A few years ago it was turkey fryers.