Blue book has absolutely nothing to do with what the IRS allows or considers acceptable. Some classic pieces are bought and sold for more than their list price when they were new. Doesn't seem like a smart decision to donate them, does it?
I don't really care to debate this but you're missing my point. Used electronics aren't worth much of anything. The IRS guidelines of 40% just happens to be about all you can get and I was just using that as an example. We are not talking about classic or esoteric equipment that people will pay an arm and a leg for (like McIntosh amps).
And why not donate it? Unless you are desperate for cash, donating to charity so that someone less fortunate might be able to pick up something they'd otherwise never be able to afford is a good thing.
I usually start with craigslist when I want to get rid of something but if I don't get any offers or only very lowball offers, I donate it instead...I just don't need the money - I want the crap out of my house.