Or, as I recently confirmed, you can buy a pretty decent complete Stafford tux outfit at JC Penny for less than $150 (excluding shoes). That's nothing to sneeze at and if you rent a couple of times, you've paid the equivalent of purchasing one that is YOURS and fits you properly (and hasn't been previously worn by some drunken wedding participant!).
Every man should own a dark suit. Even if one is casual 99.99% of the time, you will need a dark suit every once in a while for weddings, funerals, graduations, nice restaurants, etc. But with prices this cheap, there's no reason that every cruiser can't also own a tux.