Tuxedo 

When I went shopping for a tuxedo for some reason I thought I would leave spending $100 for a tuxedo rental.  It turned out that we were convinced that it would be better to buy a tuxedo which could be used again.  I already had an old tuxedo but my fiancee and of course the tuxedo store confirmed that a wedding is a one-time event so you must get a new one.  Buying a new tuxedo does faciliate the logistics however as you avoid having to return the suit the day after the wedding.  In the end I spent several hundred dollars for the tux, new shoes, a new shirt, a tie I will never wear again, etc.