A couple things you need to keep in mind that have not been explained yet.
First, the catalogue value of $1.75 that's been quoted is seldom the price at which something can be sold. These are in good condition, so perhaps they'd fetch closer to cv but still, even at best, 50% of cv is your starting point, $.85.
Second, yes, you could put them up on
ebay one at a time. 1000x.85 = $850. Sounds great. Except that selling all 1000 of them one-at a time is unrealistic, not to mention the time it would take and the
ebay fees involved.
Third, as someone suggested, selling them as a single lot, boxes and wrappers intact, might well make the most money--the pool of potential buyers is very small but if you made a sale, it might well add up to more than the number of individual envelopes you can unload on
ebay over years of selling.
Therefore, be
very careful to preserve the original wrapping and the wooden boxes. I see that some of the nails in the crates have come loose. Try to preserve things as completely as you can, including the taped paper wrappers.
Then contact the museums/organizations mentioned. Since this is a one-of-a-kind item, what one of these organizations might pay is anyone's guess. I rather doubt the American Philatelic Society would want to pay much--they depend largely on people donating stuff of this sort. Smithsonian National Postal Museum, perhaps.
But $850? No. How much less than that? Depends entirely on what the very limited market for the whole package is willing to pay.