and for $100 in our country today only available chipset is H61 from asus. I am large user of asus products. You have to know one truth about asus they are the hottest mother boards you can get literally. especially p8h61 m lx model's idle heat margins are 98 degrees. I have seen it in more than 125 boards of same model. so if you want a board with usb 3 below $100 try Asrock i don't like that brand but it's z68 boards are very good indeed.
If you still insist for USB 3.0 (no difference for daily use for basic gaming and office purpose) then check these two