There seems to be a small market for consumer motherboards with ECC.  I had planned on purchasing a new system with the ASUS M4A785TD-V EVO motherboard which got excellent reviews, was reasonably priced, and supported ECC DDR3 memory.  As this motherboard has been discontinued I took some time to find its successor.  I’m not sure the M4A78T-E counts as a successor but it is a reasonable alternative.  Finding it was somewhat difficult as ECC is not a feature many places seem to list (including newegg).  The main difference between the M4A785TD-V EVO and the M4A78T-E is the chipset combo: AMD 785G/SB710/RADEON 4200 on the former, AMD 790GX/SB750/RADEON 3300 on the latter.  For an additional $50 the ASUS M4A89GTD PRO/USB3 brings a bump to AMD 890GX/SB850/RADEON 4290 as well as USB 3 and 6Gbps SATA.  That makes it a little more future-proof but as to whether that’s worth a 50% price jump I’m skeptical.