cinghiale wrote:A brief description: We hold a single “book” of stamps of 50 pages. Around 36 of those pages are filled with sheets of stamps, with 50 to 100 stamps per sheet. Most are from the 1930s and 1940s, with 5 cent “Oppressed Nations” stamps from 1943 predominating. There are also quite a few foreign, mostly German Reich stamps in the mix.
Are these "sheets of stamps" intact sheets (or at least large blocks) like you would buy at the post office? Most US stamps of that era, especially the 3c stamps for the first-class postage rate, are not worth much more than their postage value in bulk. I go to stamp shows a few times a year, and there is usually at least one dealer with a box or folder of mint sheets of common commemorative stamps from the 1930s up through the 1980s, at no more than a small premium over face value, or even at face value. There are outliers that sell at a significant premium, of course.
You've apparently checked stamp catalogs, in which case you've probably noticed that each catalog (Scott or Michel or whatever) has a certain minimum per-stamp price. This is supposed to reflect the minimum price that a dealer might sell a single stamp for, taking into account his costs of doing business. For quantities of stamps, as in mint sheets, or packets of mixed stamps, the price per stamp drops precipitously for that kind of stamp. A dealer would probably buy them at a significant discount from face value, if he's interested in them at all.
Of course, you can use the US stamps for postage, but it's kind of awkward using 3c stamps when the first-class rate is 46c (as of tomorrow). You'd pretty much have to use them in combination with fairly recent stamps, to make up the current rate.
Also, as you're looking at the values listed in standard catalogs like Scott or Michel, keep in mind that most stamps sell at retail for a discount from catalog value. The discount depends on which catalog you're using (some catalogs have more "inflated" values than others), who you're buying from (a part-time dealer at a stamp show is likely to offer bigger discounts than a full-time dealer who sends out pricelists by mail or maintains a web site), and on the condition of the stamp. Even at a decent auction, where a stamp probably has to catalog for at least $100 in order to be listed as a separate lot, it's somewhat unusual to see a stamp sell for full catalog value. These are usually older stamps in pristine condition, well-centered and with large margins, or (for used stamps) an unusual postmark.
And of course a dealer has to buy at "wholesale" prices in order to make enough money to stay in business. For "good" but still fairly common material, I wouldn't expect to get more than half of actual retail value if I were selling to a dealer.