Obviously this is the lossy side of stamp collecting, but man, to take a haircut like that after preserving something for 20 or 30 years.
Sure there are catalogs that detail the "listed price" of a stamp, but that's the dealer price to you, not the price they'll buy it at (which is likely < 10%). Buying stamps is really easy, selling them (for their actual value) is hard. (I guess this is true for collections in general.)
Apart from the selling issue, is the searching issue. You might inherit a collection of a few thousand stamps, but it's unlikely to be sorted by value. Which means it has to be examined. By a professional. Which takes time. So there goes any value in it. Which is why a dealer will only pay pennies for a whole collection - it'll chew their time separating the wheat from the chaff.
Best thing you can get any collector to do is dispose of all the value in their collection, or clearly separate the value from the rest, before they pass.
Now me, I have books. Lots and lots of books. The kids will love inheriting those... :)
No idea if they're actually worth anything, but it gives him pleasure.
It turns out the post office, mostly doesn't actually care to count up the 1 and 2 cent stamps.
There's a group of hobbyists committing felonies out there making their own stamps and sending them out. The post office doesn't notice.
One sillier trick was, forget a stamp, it'll get returned to sender. Simply put your destination as the return and you get a free mailer.