It depends on your personal preference.
The stock cooler you get with Intel coolers are really noisy and not the best of coolers, but will keep your CPU under 70c-ish, I believe.
If you were to purchase an aftermarket cooler, you won't need anything more than around $30 as it will be a waste. The benefits of an aftermarket cooler are that they are generally much quieter, and they do provide more cooling performance depending on what you get.