Most memorably, I once consigned a 30 pound bag of stamps on paper and after the fees ended up getting about $5. Of course, that was probably more than I could find for them anywhere else and cleared out a bunch of room for me to replace with...well, probably more stamps!
And yet, for all the talk about the low value, it is very difficult to complete a collection of modern used postage stamps. While a complete collection may be worth very little money, this collecting area can provide a lifetime of fun hunting for missing stamps while costing virtually nothing. You can't beat it for an economical hobby!
I know many a stamp collector that has spent their time with 'low value' collecting areas and, you know what? They seem to be pretty happy with their hobby. Go figure :)
So is there anything else to say about this category of stamps? Let's see...covered that they're cheap, sell in bulk, and a challenging collecting area.
How about what to do with modern used US if you need to clear out some room? The best you can do is check with some local stamp dealers or hit a stamp show and try and sell it.
If you get any offer, I'd take it and run! If you have a local stamp auction that is another route. Surprisingly, your best option may be to try to sell it through a non-stamp auction, antique or collectibles store, swap meet, or any number of non-traditional stamp sales venues.
Of course, even then you're still getting very little money for your effort so you may want to just donate the stamps.
There are many charities that accept stamp donations for veteran, children and many other charities. These used postage stamps may not be valuable to us but can make a meaningful and positive difference in someone's life.