Just saw this on e-bay, a part of a package wrapper (possibly from the Bank of Cleveland) with $768.58 in (metered) postage. Have you seen anything with a higher amount of postage/insurance on a single letter or package?
https://www.ebay.com/itm/227361316060I've seen full sheets of cancelled $5 stamps ($500) that were not on a package and probably used for accumulated postage due payments rather than a single outgoing package. This piece is undated but maybe someone can estimate the date based on the older style of meter on the package.
Even the Hope Diamond package with insured value of a million dollars only had $145.29 in postage and insurance when it was mailed Registered in 1958, so this parcel with $768 postage+insurance must have held quite a substantial sum.
https://postalmuseum.si.edu/deliver...hope-diamond