The cooler master Hyper 212 evo is a great cooler, and it's fairly cheap. Only $35, and it will keep your CPU plenty cool, provided you have good case ventilation. I have it's predecessor, the Hyper 212+, and it keeps my Phenom II 1100T under 46 degrees Celsius even after running prime 95 for hours, and it idles at around 30 degrees. The evo is considerably better than the hyper 212+ in design, and I think you will like it a lot. It's also a fairly quiet cooler (hugely better than the stock am3 cooler, which is a piece of garbage in comparison)
depends on budget.
the hyper 212 is a good cooler but the fan that comes with it is noisy. and in todays low end market there is plenty of better/competition
thermolabs barham and zalman cnps 10 quite,flex are both effective at cheap.
they will get most any cpu to 4ghz without issue. for the money they are 2 of the better 1s
h60-h100 water coolers, noctua 12-14, prolimatech megahalam, true 120 will all give good cooling without deafening you or busting the wallet. the megahalem and true need good fans with 35-75+/100+cfm ratings the noctua setups come with excellent quiet fans.
XSPC Rasa 750 RS360 water cooler...