This week's book giveaway is in the Reactive Progamming forum. We're giving away four copies of Reactive Streams in Java: Concurrency with RxJava, Reactor, and Akka Streams and have Adam Davis on-line! See this thread for details.
My boss bought a lot of 3 off ebay. They were cheap, but you have to watch out for scams. Dell has an outlet site where you can buy refurbished systems and computers that were leased out and returned. Newegg offers "recertified" computer systems.