for a $100 heatsink i would recommend the Noctua NH-D14. Period.
Its an amazing cooler and can handle high OC's.
If you can get over the brown color you are fine.
ITS EXTREMELY QUIET!
I dont like loud PCs at all! So you can take off the 120mm fan on the D14 and put it as a rear exhaust in a case.
That 120mm wont make a big difference in temps(1-2C) but will make a difference in noise
4.3ghz is easily doable with the D14 and 3770k but if i were you i would not ramp up the voltages on ivy bridge processors.
TIP: Make sure you use low profile ram and not the ones which have large heatsinks(eg.Corsair Vengeance) but if you are taking off the 120mm on the D14 then it would not be necessary. BUT i still recommend low profile ram