Most guys wear tuxedos to their proms, which according to Emily Post is considered -semi-formal attire. But if you have a nice dark-colored suit, you might be able to wear that, depending on your particular dance. The school or social mores where you live may require a tux for the evening. (However, in California, people are much more unconventional and casual--so check out your options. ) If you rent a tuxedo (which can include shoes) for the evening, the going rate is $50-$150 depending upon what extras you might want. The fancier the tuxedo, the more expensive the price will be