Another thing that we should take into consideration, a customer buys a watch, the sales clerk then quickly assembles the purchase at the counter, having dug around and found the box.
I've worked in retail for many years, and I can tell you, the right box for whatever product we're talking about often does not get sold with the product. They get a lot more fussy about it with high end watches like Rolex and the like, where resale value is considerably higher with the original packaging. I remember doing inventory at the end of the year and we'd find all kinds of orphan boxes and cases with no product for them, so it does happen quite a bit.
It's quite possible the clerk just grabbed the box that said 'American girl' without checking which variant it was that was being purchased.
$59.50 in 1958 is $522 in today's money. Not expensive, but certainly not cheap.