Gigabyte GA-970 UD3P. Which sells normally for about 84 Bucks , now its on sale for 75 only.
PCPartPicker part list:
http://pcpartpicker.com/p/zWWsXL
Price breakdown by merchant: http://pcpartpicker.com/p/zWWsXL/by_merchant/
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard ($75.98 @ Newegg)
Total: $75.98
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-12-02 12:43 EST-0500
Great OC capabilities thanks to its 8+2 power phase and solid capacitors also Crossfire compatible , not sure about the USB3.0 support but I believe it supports it.