The pre-1960s have gone down in price. There are plenty of them for sale at very reasonable prices and a lot less than catalog.
The Krause catalog prices are different from the local catalog (like the Charlton catalog in Canada). I don't remember the name but I saw one in Paris last year.
I priced up about 10 French and Spanish notes that were 50% than
ebay. I am not a collector of French or pre-Euro notes otherwise would have bought a lot more. Really the only reason I bought then was because I could flip them on
ebay for almost double and then spend the money to buy notes from countries that I collect (Canada, India, Singapore, Mauritius and Ceylon/Sri Lanka).