Dell R7910 - 950€
1x E5-2603v3. Other slot empty. (2 x Heat Sink Included)
32GB ECC (2 x DDR4 2133MHz Hynix 16GB)
2 x HGST HP branded Hitachi 480GB SSD SAS3 2.5" (not attached)
PERC H330 Raid + cable (not attached)
Could convert to bare bones and...
Just made an offer of 6 for $55 each and got countered for $60. I instantly accepted. I've had the 100gb and 200gb versions of these and they've been really solid. (and tip to you all that are living in the EU, I'm using MyUS to forward the packages and it works just great).
ES Support will be tricky on all branded servers. For best compatibility, use the late revision of the QS (not ES) chips plus the newest BIOS.
Before buying the CPU, ask the CPU seller if your system is compatible with the CPU, not the server seller. They really know their stuff.