$100 is scraping the bottom of the barrel for Z68. If you want good overclock and don't mind paying $125, go with the ASRock Extreme3 Gen3http://www.newegg.com/Product/Product.aspx?Item=N82E16813157271
It's the best board at the bottom end of the price range.
If you've got to stick closer to $100 then maybe the ASRock Z68 Pro3http://www.newegg.com/Product/Product.aspx?Item=N82E16813157251
I don't necessarily prefer ASRock over ASUS, MSI, or Gigabyte in general, but in this price range those are what I would choose.