OK weird question, I was listening to the song "Johnny Fedora and Alice Bluebonnet" from the Disney short in Make Mine Music. One of the lines is
...Her beauty was sought by the girl she was bought by for $23.94.
Make mine music premiered in '46, a quick look-up shows Alice to be ~$286.92 in today's dollars. Was that typical of the era? were hats really regularly in the $300 range? or was Alice a strange expensive outlier that people of the time would have called out that song as ridiculous.
$23.94 does sound a bit steep. But bear in mind that a quality, traditionally made felt hat today will run you $200 or more.
Clothing in the past was much more expensive than it is at present. This is because the garments tended to be more structured and fitted, made out of more expensive materials (wool in the case of suits, slacks, and jackets, or, in the case of hats, felt), by more experienced and skilled workers (the American textile and garment industries of the early to mid 20th century were without equal) who earned relatively much more than the guy sewing your jeans in Indonesia. Owing to these factors, costs of production were much, much higher at pretty much any time in the past. One of the examples I like to point to is that when Abraham Lincoln bought his first suit of clothes, they cost him $60 - two or three months' wages for a common laborer - and he had to borrow money to cover the expense.
Because of this, people owned fewer garments and wore them longer. A middle class man in 1940 might have owned two or three suits and wore them in rotation until they wore out. A farmer in 1840 might have owned two, one that he saved for church, court, and going into town, and another, usually a few years old, that he worked in. Shirts were cheaper and more plentiful, but not to the degree we're familiar with; six or seven, rather than two or three dozen.
This pinboard has a few pages from a Sears catalogue from the 1940s - average prices for a lady's bonnet seem to run less than $2.50.
On searscatalogsonline.com, a 1948 catalog has similar hats for less than $4.00.
(A nearby catalog - for 1941/42 - had a car stereo in it for $23.95, by comparison.)
Now, this is Sears, the epitome of cheap clothing at the time, but still, there's a data point for you. Haute couture would doubtless have been pricier.
This is shortly after the time Schiaparelli was collaborating with Salvador Dali... and right before the Pop Art fashion consciousness of the 1950s.
I also believe that hats became kind of pricey for a brief while during (and maybe immediately after) WWII due to materials shortages, so that may be a wartime gag... but you'll have to ask someone with more fashion savvy to confirm that.