So $1 got you 120 envelops with the Minkus cachets. I've seen people try to sell individual unused covers with WWII patriotic covers on
ebay for $4-$5 each, though sometimes somone will offer several for that price. At $1 each, that would be 120x times more than they originally cost! Of course, everything was a lot less expensive back then, but that's still a big markup even considering general inflation.
Lawrence mentions Minkus marketing his covers through Gimbels, but I had never seen the promotional material before. Nice walk down memory lane. Thanks for sharing.