I think @Techspin needs at least 2 slots for HBA/NIC (if they're not builtin to the board). At least new the X11SCL-F seems a bit cheaper (and it has IPMI builtin already) at $200: mATX with three slots. The P11C-I also only has an x2 2242 M.2 slot vs full-speed/length x4 22110 on the X11SCL-F.If you want to go with Intel(Please don't kill me Intel haters) then the ASUS P11C-I is perfect. That is basically the cheapest board with ECC Support for the Intel Xeon E-2100 and E-2200 series. It has also got IPMI via the ASMB9 module. It is Mini-ITX so I hope that this is not a problem. P11C-I | Server & Workstation | ASUS Deutschland
You could also use a Supermicro X11SCA-F
So that + an E-2236/E-2246G would come in around $500 for mobo/cpu. Provantage carries the Xeon E-2200 at pretty close to list prices.