Buying a suit is not like buying a pair of jeans. Shop where such service is available. A quality suit is actually tailored to your body, and alterations are to be expected.
Conventional wisdom says that men rush through clothes shopping.
Allow time for shopping, for trying on garments, and for measurements to be taken. And just as important, allow plenty of time for the tailor to return the altered suit to you, usually about two weeks. With a man's suit, you really do get what you pay for. Buy the best quality you can afford. Choose understated, dark-colored fabrics, like navy blue or charcoal grey, in a medium weight worsted wool.