If you are not using Crossfire/SLI, the only things you need to look for in a mobo are these:
1) Power supply system/Voltage Regulator Module (the number of power phases is directly proportional to the overclockability of the motherboard. It also causes those 1% performance increases. For any motherboard, 4 phases is barely enough, 8 phases is good and above that is for serious OCers).
2) Onboard LAN/SATA controllers. Expensive motherboards will have better, faster controllers.
Performance differences are negligible.
Investing in a motherboard in the 6-8K range will keep you happy if you plan not to overclock too much (assuming you don't do SLI/Crossfire).