This spring, I was able to purchase two of the Spanish Nancy Drew books with dust jackets from Argentina. These books were in print during the 1960s in Argentina.
Both books and jackets are in rough shape, worse than how they appear in the photo, but I purchased them anyway. These books come up for sale no more than once every few years.
I now have a total of six out of the 10 Argentine Nancy Drew books with dust jackets.
Whistling Bagpipes seems to be the most common. I have seen it up for sale several times, and it sometimes closes for less than $50. For the rest of the books, you can expect to pay at least $100 up to $250 each.