http://www.amazon.com/Cool-Rock-Duke-Ellington/dp/B000001VTV
Maybe the stealthiest Ellington album ever released, you look at this and think, ah, leftovers, silly stuff, whatever, but no, there is some badass Ellingtonia all over this thing, most if not all of it from the later-y days, and the band is tight.
Get it for a penny + postage. Or if you like, pay more.
It's all stockpile stuff, and if you're thinking that maybe the riches of the stockpile was depleted by the time they released this one, well, no. I'd not put it at the "major find" level of The Jaywalker, which is kinda equally stealthy, but for waht you pay relative to what you get, hey...