What has been your smartest investment?

My husband bought a tuxedo for our wedding, which was held out of town, instead of renting one for the several days we would be away. He wore it again on New Year's Eve. The tuxedo has paid for itself — two lengthy rentals would have cost more than what we spent on it.
This tip comes from Real Simple reader KHAHLIDRA LEVISTER-PEREZ, Secaucus, New Jersey