kflach - Unless you're concerned about a top hat, derby hat or a straw boater hat, any sort of hard core preservation effort to keep a hat's shape is likley overkill. I figure a hat, expensive or otherwise, is a tool as much as it is a clothing item and meant to be used as such. I should think keeping working hats in the open air hanging on a peg is just fine and does them ample justice.
The above is not worth the two centavos in my pocket to anyone but me though I thought I'd post none-the-less.
Brass