For air cooling get a tower heatsink from Noctua that fits your price range, ranging from the NH-U9B SE2 at $50 to the fantastic NH-D14 at $80 which rivals 240mm closed loop coolers. It may be slightly hotter but it quieter, is far more reliable and has no chance of leaking and destroying all of your components. Noctua cpu coolers are the quietest, most reliable and coolest air coolers