The NH-D15 is massive overkill.
Do you have the stock cooler? If you're doing no overclocking, that's likely sufficient.
Otherwise, you just want a cheap, somewhat quiet, tower cooler. Something like the Cooler Master 212. Any of the low end Noctua coolers like the U9 or U12 would also be fine (still probably overkill).
Just get a cheap $20/$30 cooler.